Flag to indicate records missing from PAS.
Rework locking mechanism so that it works for new records (using advisory locks).
Fix address bug.
Release patient lock before updating GP and practice.
Modifications to make PasService testable.
Fix error when no CB.
PasService tests.
Tidy up tests.
Merged patient detection.
Update RELEASE notes
+ update RELEASE file
Merge branch 'master' into release/1.6

Conflicts:
	RELEASE
	components/PasObserver.php
Merge branch 'release/1.6' into develop
Use versionExistingTable method in table versioning migration.
Merge branch 'develop' into jira/3987

Conflicts:
	models/PasAssignment.php