Docs: Removed references to java 7 and debian wheezy

Related to #13694

docs/plugins/cloud-gce.asciidoc

@@ -143,7 +143,7 @@ sudo apt-get update
 wget https://download.elasticsearch.org/elasticsearch/elasticsearch/elasticsearch-2.0.0.deb
 
 # Prepare Java installation
-sudo apt-get install java7-runtime-headless
+sudo apt-get install java8-runtime-headless
 
 # Prepare Elasticsearch installation
 sudo dpkg -i elasticsearch-2.0.0.deb
@@ -412,7 +412,7 @@ Set the service account scopes when creating the machine:
 --------------------------------------------------
 knife google server create www1 \
     -m n1-standard-1 \
-    -I debian-7-wheezy-v20131120 \
+    -I debian-8 \
     -Z us-central1-a \
     -i ~/.ssh/id_rsa \
     -x jdoe \

docs/plugins/discovery-azure.asciidoc

@@ -353,14 +353,14 @@ Once connected, install Elasticsearch:
 [source,sh]
 ----
 # Install Latest Java version
-# Read http://www.webupd8.org/2012/01/install-oracle-java-jdk-7-in-ubuntu-via.html for details
+# Read http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html for details
 sudo add-apt-repository ppa:webupd8team/java
 sudo apt-get update
-sudo apt-get install oracle-java7-installer
+sudo apt-get install oracle-java8-installer
 
 # If you want to install OpenJDK instead
 # sudo apt-get update
-# sudo apt-get install openjdk-7-jre-headless
+# sudo apt-get install openjdk-8-jre-headless
 
 # Download Elasticsearch
 curl -s https://download.elasticsearch.org/elasticsearch/elasticsearch/elasticsearch-2.0.0.deb -o elasticsearch-2.0.0.deb

docs/reference/getting-started.asciidoc

@@ -101,7 +101,7 @@ With that out of the way, let's get started with the fun part...
 
 == Installation
 
-Elasticsearch requires at least Java 7. Specifically as of this writing, it is recommended that you use the Oracle JDK version {jdk}. Java installation varies from platform to platform so we won't go into those details here. Oracle's recommended installation documentation can be found on http://docs.oracle.com/javase/8/docs/technotes/guides/install/install_overview.html[Oracle's website]. Suffice to say, before you install Elasticsearch, please check your Java version first by running (and then install/upgrade accordingly if needed):
+Elasticsearch requires at least Java 8. Specifically as of this writing, it is recommended that you use the Oracle JDK version {jdk}. Java installation varies from platform to platform so we won't go into those details here. Oracle's recommended installation documentation can be found on http://docs.oracle.com/javase/8/docs/technotes/guides/install/install_overview.html[Oracle's website]. Suffice to say, before you install Elasticsearch, please check your Java version first by running (and then install/upgrade accordingly if needed):
 
 [source,sh]
 --------------------------------------------------

docs/reference/setup.asciidoc

@@ -74,14 +74,12 @@ $ bin/elasticsearch -Des.index.refresh_interval=5s --node.name=my-node
 == Java (JVM) version
 
 Elasticsearch is built using Java, and requires at least
-http://www.oracle.com/technetwork/java/javase/downloads/index.html[Java 7] in
+http://www.oracle.com/technetwork/java/javase/downloads/index.html[Java 8] in
 order to run. Only Oracle's Java and the OpenJDK are supported. The same JVM
 version should be used on all Elasticsearch nodes and clients.
 
-We recommend installing the *Java 8 update 20 or later*, or *Java 7 update 55
-or later*.  Previous versions of Java 7 are known to have bugs that can cause
-index corruption and data loss.  Elasticsearch will refuse to start if a
-known-bad version of Java is used.
+We recommend installing the *Java 8 update 20 or later*.
+Elasticsearch will refuse to start if a known-bad version of Java is used.
 
 The version of Java to use can be configured by setting the `JAVA_HOME`
 environment variable.

docs/reference/setup/as-a-service-win.asciidoc

@@ -42,7 +42,7 @@ service will be installed. This information is made available during install:
 --------------------------------------------------
 c:\elasticsearch-{version}\bin>service install
 Installing service      :  "elasticsearch-service-x64"
-Using JAVA_HOME (64-bit):  "c:\jvm\jdk1.7"
+Using JAVA_HOME (64-bit):  "c:\jvm\jdk1.8"
 The service 'elasticsearch-service-x64' has been installed.
 --------------------------------------------------
 

docs/reference/setup/as-a-service.asciidoc

@@ -43,17 +43,17 @@ sudo /etc/init.d/elasticsearch start
 [float]
 ===== Installing the oracle JDK
 
-The usual recommendation is to run the Oracle JDK with elasticsearch. However Ubuntu and Debian only ship the OpenJDK due to license issues. You can easily install the oracle installer package though. In case you are missing the `add-apt-repository` command under Debian GNU/Linux, make sure have at least Debian Wheezy and the package `python-software-properties` installed
+The usual recommendation is to run the Oracle JDK with elasticsearch. However Ubuntu and Debian only ship the OpenJDK due to license issues. You can easily install the oracle installer package though. In case you are missing the `add-apt-repository` command under Debian GNU/Linux, make sure have at least Debian Jessie and the package `python-software-properties` installed
 
 [source,sh]
 --------------------------------------------------
 sudo add-apt-repository ppa:webupd8team/java
 sudo apt-get update
-sudo apt-get install oracle-java7-installer
+sudo apt-get install oracle-java8-installer
 java -version
 --------------------------------------------------
 
-The last command should verify a successful installation of the Oracle JDK. If you want to install java8, you can call `apt-get install oracle-java8-installer`
+The last command should verify a successful installation of the Oracle JDK.
 
 
 [float]