Update drafts JS to operate as a editor plugin

For consideration

This splits the current drafts.js in to two files.  

The first is the standard drafts.js which is only used by quick reply when it is not using the editor (e.g. a plain text box).  This is a simplified version of the current draft.js.

The new file is drafts.plugin which loads with and is called directly by the editor.  It uses the events as provided by the editor instead of trying to add new event handlers external to the editor.  This should make the autosave better behaved.