Make sure global_config['_xmpp_mode'] actually exists before we test it out.
Make sure global_config['_xmpp_mode'] actually exists before we test
it out.

synety-jdebp/rtpproxy,sippy/rtpproxy,jevonearth/rtpproxy,sippy/rtpproxy,dsanders11/rtpproxy,sippy/rtp_cluster,dsanders11/rtpproxy,jevonearth/rtpproxy,dsanders11/rtpproxy,synety-jdebp/rtpproxy,synety-jdebp/rtpproxy,sippy/rtpproxy,jevonearth/rtpproxy,jevonearth/rtpproxy,synety-jdebp/rtpproxy,sippy/rtp_cluster