pjsip: Fixed keeping dialog up when in-dialog request got 408

Ignore-this: 69789ae03715524e941217790402ccee

darcs-hash:20130808155326-56b4d-0527131a25cbfd0e64c8a3ae078e061248bf1834
pjsip: Fixed replying to re-INVITE after it was cancelled

Ignore-this: ea16cd5f3828b4bc7ea3361c59171c9e

darcs-hash:20130809081502-56b4d-b1c1036a8d55f558eff0a713ce1f996f95373b17
Improved ICECandidate and ICECheck string representation

Ignore-this: efe8bfe5f131b7d1dbc9f18e8a929d91

darcs-hash:20130809085220-56b4d-4d1ade636c7d3bebb7f8b5e56f1c622f2670ce16