Updated morray, added scenario feature

Hey, I was missing the feature of easily defining which fields should be included during a request, so I used the scenario feature of MorrayBehavior to make this happen. 
This enables you to:
- specify which fields should be used in each request 
- include virtual attributes (image url's for example)
- determine the order in which the fields are sorted

Please check if everything runs smoothly at your pc and if you think this is useful =)