Additional work on EAS security

* Add more final plumbing for exchange security
* If policies are supported, we now check to see if they are active;
  if so, we acknowledge this to the server, after which we are given a
  final policy key which can be used for syncing

Change-Id: I5992c790294e35b5ec5343c7665e2e7fd31a75ca
4 files changed