Fixed issue where signin movement cancellation still worked even if data.yml was disabled

Minor (but necessary) changes to the code.

Updated:
- Players can't move until they've signed in
- Registered passwords get hashcoded and then stored.

Some Minor improvements to the code.
Removed the menu and /menu command since it's not necessary for this plugin.

Admins can now Enable or Disable registration and signing in with:
/vitalregister data.yml <disable/enable>