Give vagrant test boxes 3gb of ram

Now that Elasticsearch defaults to 2gb heaps those boxes need more ram,
especially opensuse-13 for some reason. It has failed to run the
packaging tests ever since the change.....

Vagrantfile

@@ -78,8 +78,8 @@ Vagrant.configure(2) do |config|
   config.vm.synced_folder ".", "/vagrant", disabled: true
   config.vm.synced_folder ".", "/elasticsearch"
   config.vm.provider "virtualbox" do |v|
-    # Give the boxes 2GB so they can run our tests if they have to.
-    v.memory = 2048
+    # Give the boxes 3GB because Elasticsearch defaults to using 2GB
+    v.memory = 3048
   end
   if Vagrant.has_plugin?("vagrant-cachier")
     config.cache.scope = :box