Fix Bridge application and AMI Bridge action error handling.

Fix Bridge application and AMI Bridge action error handling.

* Fix AMI Bridge action disconnecting the AMI link on error.

* Fix AMI Bridge action and Bridge application not checking if their
masquerades were successful.

* Fix Bridge application running the h-exten when it should not.

* Made do_bridge_masquerade() return if the masquerade was successful so
the Bridge application and AMI Bridge action could deal with it correctly.

* Made bridge_call_thread_launch() hangup the passed in channels if the
bridge_call_thread fails to start.  Those channels would have been
orphaned.

* Made builtin_atxfer() check the success of the transfer masquerade
setup.

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@369282 65c4cc65-6c06-0410-ace0-fbb531ad65f3