bugfix. Properly cancel when only '100 trying' has been received
bugfix. Properly cancel when only '100 trying' has been received

- CANCEL request was not being sent if only '100 trying' was received.
- RTCSession.terminate() was calling RTCSession::close() twice.
- Deleted duplicated state verification in RTCSession::receiveInviteResponse()

vconsult/JsSIP,rusekr/JsSIP,DrumTechnologiesLtd/JsSIP,voxbone/JsSIP,dpocock/JsSIP,AaronZhangL/JsSIP,tqcenglish/JsSIP