CHANGES: Update changes log to include new bridge fields added in r404042


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@407419 f38db490-d61c-443f-a65b-d21fe96a405b
UPGRADE: Note change in behavior for device state subscriptions

git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@407423 f38db490-d61c-443f-a65b-d21fe96a405b