Integrate AuthenticationProvider

[Mihael Schmidt]

The AuthenticationProvider needs to be an Interface which gets the HTTP message passed for retrieving the authentication token (either a real token or username/password).

API : pointer droplet_auth_retrieveToken(pointer httpMessage)

The AuthenticationProvider needs to be configured at the service.

API: void droplet_service_setAuthencationProvider(pointer authProvider)

And the configured AuthenticationProvider needs to be called before passing the message to the endpoint, see Router.

The configuration needs to be extended by an AuthenticationProvider and the xml configuration provider needs to support a configurable AuthenticationProvider (as is the logger support, via reflection).