Anonymous Editor Acquisition v2

* Remove the post-edit bucket and variant
* Rename the pre-edit variant to pre-edit v1
* Add the pre-edit v2 variant
* Add the mediaWiki.gettingStarted.Bucket enumeration
* Update the clients of the mediaWiki.gettingStarted.user.getBucket
  function to use the new enumeration
* Also, update the mediaWiki.gettingStarted.user.getBucket function to
  use the penultimate character of the user's token
* Refactor the pre-edit v1 variant so that all user actions are handled
  by methods on the mediaWiki.gettingStarted.anonymousEditorAcquisition
  singleton class
* Remove logEvent wrapper

Change-Id: Ia9c0519c29c8787aa71f8fca2821c9a232affc90
Merge "Anonymous Editor Acquisition v2"