fixed TokenEndpoint errors 

. Changed testcase directory name "unittest by unittestcase" for conflict with the unittest package.
. In tests are added one for TokenEndpointTest
. It removes the reference to "self" in method of TokenEndpoint create_token_response to recover query_params
. It changes the TokenEndpoint validation for "grant_type" as it was inverted the comparison between "body_params and query_params"
. TokenEndpoint The body_params in {} is allowed if there is no value nungun