Use Delegator event helpers in Document

Author: tilgovi

src/plugin/document.coffee

@@ -2,9 +2,10 @@ Annotator = require('annotator')
 
 
 class Annotator.Plugin.Document extends Annotator.Plugin
+  events:
+    'beforeAnnotationCreated': 'beforeAnnotationCreated'
 
   pluginInit: ->
-    @annotator.subscribe('beforeAnnotationCreated', this.beforeAnnotationCreated)
     this.getDocumentMetadata()
 
   # returns the primary URI for the document being annotated