oauth2server: oauth2server improvements

* Removes the oauth parameter from some functions.

* Adds '/' to the endpoints that need it in the test_provider.

* Changes some 403 to 401 in the test_provider.

* In some helpers functions the url_for is used in order not
  to have a url hard-coded.

* Tests the test_provider case

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>

oauth2server: oauth2server improvements

* Removes the oauth parameter from some functions.
* Adds '/' to the endpoints that need it in the test_provider.
* Changes some 403 to 401 in the test_provider.
* Tests the test_provider case.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
restful: decorator improvement

* Improves require_api_auth decorator by clearing the session
  and returning the response at the end.

* Removes the bound_instance_ parameter, removes the
  require.oauth from the return statement and the returned
  function now contains only the *args and the **kwargs.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>

restful: decorator improvement

* Improves the require_api_auth decorator by clearing
  the session and returning the response at the end.

* Removes the bound_instance_ parameter, removes the
  request.oauth from the return statement and the
  function returned now contains only *args and **kwargs.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>

restful: decorator improvement

* The require_api_auth now calls the require_auth method
  from flask-oauthlib.

* Removes oauth parameter from require_oauth_scope method and
  replaces it with request.oauth.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
documents: documents REST API changes

* Removes oauth parameter from REST API functions.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
deposit: deposit REST API changes

* Removes oauth parameter from REST API functions.
* Adds base_url to a test_registration.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
tags: API and REST API fixes

* Removes oauth parameter from REST API methods.

* Ensures tests are run OK.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>

tags: API and REST API fixes

* Removes oauth parameter from REST API methods.
* Adds a uid parameter to the method that attaches
  tags to records.
* Ensures tests are run OK.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>