Load data from xwing-data using manage.py command

[OskarBreach]

Replace the migration 0002_load_data with a manage.py command, which can be re-run independently of the migrations.

Writing custom django-admin commands.

[Tarnal12]

Done. The old migration has been removed, and a new command added (xwingdata/management/commands/populatedata.py)

Runs basically the same code as before but can be done independently of migrations.

[OskarBreach]

Fixed by commit https://github.com/OskarBreach/hit-hit-crit/commit/49e0099d73dbbe71fe0b4a7631c2a90aa59a226b