Add Optional user setable transfer destination number
example usage:

<application="limit" data="<realm> <id> <max> [transfer_destination_number]"/>
existing functionality is not changed... if limit is exceeded and 
transfer_destination_number is not specified call will still be redirected to limit_exceeded

Also add new channel variable limit_original_destination which is set to the 
destination_number before mod_limit does its thing



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@7256 d0543943-73ff-0310-b7d9-9358b9ac24b2