Not sure about this.. they're doing the same thing I was originally doing in the view itself, so on the one hand it makes sense to keep them here.

On the other hand, it's a bit weird that the `WATCHMAN_CHECKERS` references `watchman.views`. I think I'd prefer to move them into `checks.py`. We could make the other methods in there "private" (`__check_databases`, `__check_database`, etc.) to make it more obvious which you can use.

On a separate note, I think I'd prefer to keep the naming consistent: `DEFAULT_CHECKS`, `WATCHMAN_CHECKS`, `checks.py`, etc.

Let me know what you think.