Switch off dynamic bucket mode when selecting an annotation by clicking on the highlight

 * Moved the dynamicBucket variable inside the scope for the AppController
 * In services, add a method for switching the dynamic bucked mode on and off
 * Add an RPC for doing the same
 * Add a method in the host frame for doing the same
 * When selecting annotations/highlights by clicking on the highlight in the host
   document, call this method to switch off dynamic mode.

This fixes #712.