[prep-release-3.1.0-b2] Update version to 3.1.0-b2
[prep-release-3.1.0-b2] Add migration for 3.1.0-b2
[prep-release-3.1.0-b2] Prepare Changelog
[prep-release-3.1.0-b2] Add changelog for 3.1.0-b2
[prep-release-3.1.0-b2] Prepare development of 3.1.0-b3
Merge branch 'prep-release-3.1.0-b2' into develop-ascraeus

* prep-release-3.1.0-b2:
  [prep-release-3.1.0-b2] Prepare development of 3.1.0-b3
  [prep-release-3.1.0-b2] Add changelog for 3.1.0-b2
  [prep-release-3.1.0-b2] Prepare Changelog
  [prep-release-3.1.0-b2] Add migration for 3.1.0-b2
  [prep-release-3.1.0-b2] Update version to 3.1.0-b2