Various bug fixes and new features.

- Configures asset pipeline and move all assets so that they're now used
  by it.
- Implement password reminders.
- Fix user update forms so that blank passwords aren't saved and the
  password field is automatically hashed.
- Refactor user model validation so that there are now two sets of
  validation rules, one for creating and one for updating.
- Remove extra folder layer around layouts.
- Add a base controller for the Admin controllers API.
- Add user delete functionality.
- Remove record deletion macro in favor of restfulized links js script.
- Various other small fixes and tweaks.