Merge pull request #856 from GhostManager/feature/assignment-ordering

Updated for release

Added tests for the advisory lock

Switched to `bulk_update` for a better migration

Added PostgreSQL advisory lock to handle simultaneous entries

Set role as not required in form to allow formset validation

Fixed regression in tests

Made migration more resilient

Lock roles for the atomic operations

Switched to using `check` until Django upgrade

Updated tests for `ProjectRole` changes

Added `position` field to `ProjectRole`

Merge pull request #853 from GhostManager/hotfix/tinymce-dark-mode

Added reference for TinyMCE upgrades

Styles clean up