Reduce CLI spam of "Extension Changed" device state messages.

Reduce CLI spam of "Extension Changed" device state messages.

Asterisk 11 follows RFC3265 that states that after every subscribe or resubscribe a notify should be sent.
Thus the console if filled continuously with the following after every subscribe;
  == Extension Changed 8512[phones] new state IDLE for Notify User cisco1

In Asterisk 1.8 only changes would be sent. Thus only when a device state changed was anything emitted to the console.

fix:
Only print to console when device state isn't forced.

(closes issue ASTERISK-20706)
Reported by: alecdavis
Tested by: alecdavis
alecdavis (license 585)
........

Merged revisions 376540 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@376541 65c4cc65-6c06-0410-ace0-fbb531ad65f3