Fix Registration Failure When A Peer And TLS Are Used

If a peer is used in a register line and TLS is defined as the transport, the
registration fails since the transport on the dialog is never set properly
resulting in UDP being used instead of TLS.

This patch sets the dialog's transport based on the transport that was defined
in the register line.  If the register line does not specify a transport, the
parsing function for the register line always defaults back to UDP.

(closes issue ASTERISK-21964)
Reported by: Doug Bailey
Tested by: Doug Bailey
Patches:
    asterisk-21964-set-reg-dialog-transport.diff
					by Michael L. Young (license 5026)


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@396240 f38db490-d61c-443f-a65b-d21fe96a405b