Document task id's as string in the rest spec

rest-api-spec/src/main/resources/rest-api-spec/api/tasks.cancel.json

@@ -8,7 +8,7 @@
       "parts": {
         "task_id": {
           "type": "string",
-          "description": "Cancel the task with specified id"
+          "description": "Cancel the task with specified task id (node_id:task_number)"
         }
       },
       "params": {
@@ -25,8 +25,8 @@
           "description": "Cancel tasks with specified parent node."
         },
         "parent_task": {
-          "type" : "number",
-          "description" : "Cancel tasks with specified parent task id. Set to -1 to cancel all."
+          "type" : "string",
+          "description" : "Cancel tasks with specified parent task id (node_id:task_number). Set to -1 to cancel all."
         }
       }
     },

rest-api-spec/src/main/resources/rest-api-spec/api/tasks.list.json

@@ -7,8 +7,8 @@
       "paths": ["/_tasks", "/_tasks/{task_id}"],
       "parts": {
         "task_id": {
-          "type": "number",
-          "description": "Return the task with specified id"
+          "type": "string",
+          "description": "Return the task with specified id (node_id:task_number)"
         }
       },
       "params": {
@@ -29,8 +29,8 @@
           "description": "Return tasks with specified parent node."
         },
         "parent_task": {
-          "type" : "number",
-          "description" : "Return tasks with specified parent task id. Set to -1 to return all."
+          "type" : "string",
+          "description" : "Return tasks with specified parent task id (node_id:task_number). Set to -1 to return all."
         },
         "wait_for_completion": {
           "type": "boolean",