Fix test failures if you unregistered via GUI.

Unregistering via the GUI deletes /etc/pki/entitlement, which causes
several tests to fail. (but is also a good warning for tests that are
loading from the filesystem)

Use new dep injection to setup the entitlement/product directory the
components should recieve when requested. Done in the test fixture so
any test class inheriting from it won't load things from disk.
Remove  ent/prod dir arguments to CLI commands.

This was purely for testing. Use dependency injection instead.
Merge pull request #530 from candlepin/dgoodwin/test-improvement

Dgoodwin/test improvement