Cleanup skinny callinfo.

Cosolidated the working out of the callinfo to be sent into
transmit_callinfo. Replaced ambiguous sub->outgoing with calldirection
which can be SKINNY_INCOMING or SKINNY_OUTGOING (same value as the
skinny protocol). 


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@316519 65c4cc65-6c06-0410-ace0-fbb531ad65f3