implemented equals and hashCode for Resource/Id to enable them be used in Choices

Hi Sebastien,
I'm using the Resource class quite straight-forward as model-beans in ```RadioChoices``` for filtering features for my scheduler instance on page. To let the Choices be able to select Resource when clicked/chosen, I implemented equals/hashCode for ```Resource``` and ```Id```.

I always let equals/hashCode generate by Eclipse, and I'm not sure if they fit your style, so please have a short look at it.

Thanx for merging...
best regards
Patrick