Introduction of setup and teardown events for ve.ce.View nodes

* modules/ve/ve.Node.js - remove ve.EventEmitter mixin
* modules/ve/ve.dm.Node.js - added ve.EventEmitter mixin
* modules/ve/ce/ve.ce.BranchNode.js - make updateTagName use newly added
  events

Change-Id: I349155b8e986fe09b615bb5f0617409d723936ef
Merge "Introduction of setup and teardown events for ve.ce.View nodes"