* Changed 'JsonUtil' to explicitly encode db.Models (encoding Model.key().id() is automatically inserted into every model that is encoded)
* Removed the bean layer, now everything works directly with the Model objects. To support this, all Models that can be serialised need to define a 'jsonFields()' method that returns a list of properties to encode.
* Added 'JsonSingleResult' and 'JsonListResult' decorators, to make returning JSON easier from the resources
* Moved some application logic to the font-end, because of the removal of the bean layer. I'm not sure if this is appropriate so have a look and see what you think