res_pjsip_transport_websocket: Ensure secure Websocket clients can be called.

This change enforces the transport in the Contact header for Websocket clients.
Previously a client may provide a transport of 'ws' when it is actually using
a transport of 'wss'. This would cause outgoing calls to fail as the existing
connection could not be found.
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Merged revisions 421931 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421932 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@421933 65c4cc65-6c06-0410-ace0-fbb531ad65f3