Start 0.10.0 development
Allow Pilots to exist without owners

Logging in and then trying to set a Pilot's owner to None for characters that user doesn't own anymore leads to sad times.
Merge branch 'bug/ownerless-pilots' into release

* bug/ownerless-pilots:
  Allow Pilots to exist without owners
  Start 0.10.0 development
Release 0.9.9.1

Fix for bug not allowing users to log in when they don't own a character anymore.