Iax2 prune realtime had issues.  If "iax2 prune realtime all" was called, it would appear like the command was successful, but in reality nothing happened.  This is because the reload that was supposed to take place checks the config files, sees no changes, and does nothing.  If there had been a change in the the config file, the realtime users would have been marked for deletion and everything would have been fine.  Now prune_users() and prune_peers() are called instead of reload_config() to prune all users/peers that are realtime.  These functions remove all users/peers with the rtfriend and delme flags set. iax2_prune_realtime() also lacked the code to properly delete a single friend.  For example. if iax2 prune realtime <friend> was called, only the peer instance would be removed. The user would still remain.  

(closes issue #14479)
Reported by: mousepad99
Review: http://reviewboard.digium.com/r/176/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@178767 65c4cc65-6c06-0410-ace0-fbb531ad65f3