api: migrating to the manager model
storage: add exception for handling instance not found errors
storage: use InstanceNotFoundError in MongoDBStorage.retrieve
managers/ec2: use InstanceNotFoundError
tests/managers: implement remove_instance in FakeManager
api: migrate remove_instance to the new manager model
tests/managers: implement bind in the FakeManager
api: port bind to the new managers model
tests/managers: implement unbind in FakeManager
api: port unbind to the managers model
managers/ec2: return dict on info()
tests/manager: implement info
tests/manager: improve is_ok implementation
tests/managers: fix info implementation
api: port info to the manager model
managers/ec2: change is_ok to status
tests/managers: implement status
tests/managers: add state to the instance and adjust status
api: implement status
api: delete some dead code