Skinny: Milestone 3: Calls management

As of now, this is only proof of concept. How to test:
- only one phone registred
- call originate skinny/internal/7628 &delay_echo(100) from console
- answer
- test the echo
- hangup

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@16779 d0543943-73ff-0310-b7d9-9358b9ac24b2