Entry points are fantastic, and they're a great way for us to allow

third parties to integrate their own plugins with Review Board.

Unfortunately, if there's a VersionConflict present in the install, no

entry points will load, even if things will otherwise work. The result

of this is that none of our built-in services will work properly.
This change moves our built-ins directly into the registry's

get_defaults() method, rather than using entry points. Any third-party

services will still be loaded from entry points afterwards.

Started with a fresh database and virtualenv. Saw that built-in services

were available in the "Add Repository" form.