Anvil v0.2.0

This release has breaking API changes.

New in this version:

• Important! Registering a listener to a registry now requires you to add .register(); at the end of the call. Plugins will fail silently if this is not done. This was done to make it simpler to specify the scope and order for a listener.
• Added ordering to registry listeners.
• Added @RegistryScoped annotation.
• Keys now require a namespace to register, this is to make inter-plugin data access easier and pave the way for future placeholder stuff.
• TimeFormatService now uses FormatResult for some return types. Use toString() to capture the current state of the FormatResult as a String.
• Updated MongoDB drivers
• Started using checker framework

Removed in this version:

• Nuked the Plugin interface. This interface added unnecessary weight to the API and wasn't being used anywhere.
• The PermissionService no longer has a generic type. This service only has one boolean method to check a permission for the provided subject. Checking the type of this parameter is now done at runtime.