* Added MethodViewResolver
By subclassing RestyResolver and modifying its `resolve_function_from_operation_id` method, it is now possible to use automatic routing functionality with Flask's MethodView together with MethodViewResolver.
* Add MethodView example
* Add tests for methodview
* add documentation on how to use MethodViewResolver
removed test_decorators and test_parameter (this test is useless now);
removed the request/response containers and add new request response classes;
created a abstract api class and a api flask class;
derived classes will implements the get_response/get_request methods that will convert framework req/resp types to connexion req/resp types;
moved the jsonifier from produces to flask api;
created a abstract app class and a app flask class;
changed all validators to use the ConnexionRequest instead flask request;
changed the problem function to generate a ConnexionRequest;
created a new user variables container called context (this is a property of ConnexionRequest). this will be passed as kwargs to all operations functions;
this context is used on authentication;
fixed all tests to new API;
some changes that I did may not be documented in this commit.
Without sanitization e.g. OData query parameters, such as $skip, $top,
$filter cannot be passed to the controller (except by use of **kwargs).
Fixes: zalando/connexion#334
