Add Asterisk TestSuite event hooks to support ConfBridge testing

This patch adds initial testsuite event hooks so that ConfBridge tests
can be executed in the Asterisk TestSuite.

(issue ASTERISK-19059)
........

Merged revisions 348846 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@348848 65c4cc65-6c06-0410-ace0-fbb531ad65f3