Fix a variety of ref counting issues

This patch resolves a number of ref leaks that occur primarily on Asterisk
shutdown.  It adds a variety of shutdown routines to core portions of
Asterisk such that they can reclaim resources allocate duringd initialization.

Review: https://reviewboard.asterisk.org/r/2137
........

Merged revisions 374177 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 374178 from http://svn.asterisk.org/svn/asterisk/branches/10
........

Merged revisions 374196 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@374197 65c4cc65-6c06-0410-ace0-fbb531ad65f3