Many minor tweaks

- Update JsSIP lib (several minor fixes)
- Improve behaviour on authorisation failures (stop croc object)
- Deprecated connect/disconnect methods on croc object (use start/stop
  instead)
- Minor improvements to jsdoc
- Ignore "application" m-lines in SDP (no longer sets port to zero)
- Fixed problem in forking tests due to re-using instance UUID
Improve media source detection on startup

Fixes #14, though the new detection mechanism only works in Chrome 30+.