Self service view, update and cancel for CiviEvent

This issue addresses the MIH found at http://wiki.civicrm.org/confluence/display/CRM/Self+service+view%2C+update+and+cancel+for+CiviEvent+and+improvements+to+event+badges?focusedCommentId=268009478#comment-268009478

• parts 2 & 3, not the badge part 1 - this feature would allow either authorized or anonymous registrants to change (selected/configured) Events they've registered for - to either cancel or transfer the registration to another contact/person. Where events allow for multiple participant registration, each one will be allowed to cancel/transfer. Re: configuring Events for this, only events that allow for online registration can be set up to allow for self cancel/transfer, the admin can also define how many hours before the event start datetime one can do a self-cancel/transfer.
  See attached Summary, Schema updates, UI model, workflow for details