Add setsubstate_ringin.

Added setsubstate_ringin. skinny_call now calls sss_ringin rather than inline.
Fixed previous issue so that setsubstate_connected now use SUBSTATE_RINGIN
to determine is an AST_CONTROL_ANSWER should be queued.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@316584 65c4cc65-6c06-0410-ace0-fbb531ad65f3