Replace res_ais with a new module, res_corosync.

This patch removes res_ais and introduces a new module, res_corosync.
The OpenAIS project is deprecated and is now just a wrapper around
Corosync.  This module provides the same functionality using the same
core infrastructure, but without the use of the deprecated components.

Technically res_ais could have been used with an AIS implementation other
than OpenAIS, but that is the only one I know of that was ever used.

Review: https://reviewboard.asterisk.org/r/1700/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@354046 65c4cc65-6c06-0410-ace0-fbb531ad65f3