Post Editor: adds autosave parameter to outbound queries

When the post editor decides to save automatically, add an autosave parameter to
the API query.

This allows the server to differentiate between autosaves, and manual saves.

client/lib/posts/actions.js

@@ -211,7 +211,7 @@ PostActions = {
 				}
 			);
 		} else {
-			PostActions.saveEdited( null, null, callback, { recordSaveEvent: false } );
+			PostActions.saveEdited( null, null, callback, { recordSaveEvent: false, autosave: true } );
 		}
 	},
 
@@ -347,6 +347,9 @@ PostActions = {
 			context: 'edit',
 			apiVersion: '1.2',
 		};
+		if ( options && options.autosave ) {
+			query.autosave = options.autosave;
+		}
 
 		if ( ! options || options.recordSaveEvent !== false ) {
 			recordSaveEvent( context ); // do this before changing status from 'future'