don't infer contract via Op::Contract anymore, but via Op.contract_class. Op::present is what used to be Op::contract.
TODO: sort out if we need to initialise contract_class = Form.clone. how can we warn users if they didn't setup a contractß
that sucks.
Crud::model_name becomes ::model_class to prevent name clash with AM::Naming.
add Op::Responder, Representer and Controller.
more untested controller behaviour. tests coming as soon as the API is stable.
more untested.:)
Merge branch 'master' into inheritable-contract

Conflicts:
	lib/trailblazer/operation/worker.rb
add tests for Responder and infer model name via CRUD::model_class.to_s.
add untested Controller#respond. it's all gonna be great.