res_pjsip_session: Add additional checks for delaying session refreshes.

There are certain situations which no checks existed for which need to prevent
session refreshes. This includes sending a session refresh with SDP before SDP
negotiation has completed and sending a session refresh before the dialog itself
has been established. Checks for these have been added.

Additionally COLP related UPDATEs were including SDP when it is not needed.

Review: https://reviewboard.asterisk.org/r/4008/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@424056 f38db490-d61c-443f-a65b-d21fe96a405b