Mix mixins during object construction to make them available as early as possible.
Change DatabaseBehavior::isSupported() implementation

- Only register the behavior as a mixin for the row if it's supported on the table.
-  DatabaseBehaviorInterface::isSupported() only returns false if the behavior is mixed with the table and it's not supported. If the behavior is mixed with a row, always return true.
Refactor KDispatcherAuthenticatorInterface

- Add authenticateRequest method
- Add signResponse method
- Extend KDispatcherAuthenticatorInterface from KBehaviorAbstract
re #91: Log user in from the JWT token in the request if possible