add execute_on_originate var '<app> <arg>' to run in origination thread or '<app>::<arg>' to run async. also originating_leg_uuid variable to show the uuid of the originating leg on an outbound channel

FS-2989: Places ;fs_path= within the contact string <...> when using NDLB-connectile-dysfunction-2.0, instead of just appending to the end of the contact string.

         - MFC-R2 requires tone signaling that gets screwed sometimes
           if the EC is enabled during call setup.
         - EC is now enabled only when switching to a state requiring
         media (UP and PROGRESS_MEDIA)
         - The logic is aware of EC persist option in Wanpipe
         - Improved logging in ftmod_wanpipe to print EC state on startup

The defaults for these keys are empty.  This change allows them to be
set empty in the XML config without error.