Use an autogenerated ID for the User fixture.
Use autogenerated IDs for the Workflow fixtures.
Use autogenerated IDs for the RunPort fixtures.
Use autogenerated IDs for the Run fixtures.
We can't use autogenerated IDs for DJ fixtures.

No idea why, but add a comment for future reference.
Add a test for Run#initialized?
Merge branch 'better-fixtures' into next

* better-fixtures:
  We can't use autogenerated IDs for DJ fixtures.
  Use autogenerated IDs for the Run fixtures.
  Use autogenerated IDs for the RunPort fixtures.
  Use autogenerated IDs for the Workflow fixtures.
  Use an autogenerated ID for the User fixture.

Conflicts:
	test/unit/taverna_player/run_test.rb