Allow Timer B to be set on the peer, and ensure SIP rules are followed (or...

Allow Timer B to be set on the peer, and ensure SIP rules are followed (or warn) in comparison to Timer T1.

(closes issue #16643)
 Reported by: nahuelgreco
 Patches: 
       20100204__issue16643.diff.txt uploaded by tilghman (license 14)
 Tested by: oej


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@246724 65c4cc65-6c06-0410-ace0-fbb531ad65f3