Stop 487 responses being propagated after call diversion
Add a SAS trail to any third-party REGISTER messages sent
Correction to SAS trail fix - get the trail from the request
Applying code review feedback
Move our code to use PJSIP group locks correctly
Improve commenting
Code-review mark-ups
Clarify enter_context/exit_context behavior
Merge pull request #113 from Metaswitch/use_pjsip_group_locks

[Reviewer: Mike] Use PJSIP group locks (fixes #112)
Fix compile issue
Merge branch 'dev' of github.com:Metaswitch/sprout into issue90
Fixes #111 - add locking around authorized_ids/default_id members
Merge pull request #110 from Metaswitch/sas_trail_on_registers

{Reviewer: Mike} SAS trail on third-party REGISTERs
Merge pull request #117 from Metaswitch/issue111

[Reviewer Matt] Fixes #111 - add locking around authorized_ids/default_id members
Remove default for dissociate parameter in cancel_pending_uac_tsx
Merge pull request #116 from Metaswitch/issue90

[Reviewer Matt] Issue 90 - stop 487 responses propagating upstream after a redirect.
Merge dev branch and fix merge conflicts