Store credentials required to satisfy a given auth scheme.

        Args:
          scheme (str): The name of the Authentication scheme.
          **params: parameters for the specified scheme.

        Returns:
          True if parameters are set successfully (note that this doesn't mean
          the credentials are valid)
          False if the scheme specified is not supported

def authorize(self, scheme, **params):
        """Store credentials required to satisfy a given auth scheme.

        Args:
          scheme (str): The name of the Authentication scheme.
          **params: parameters for the specified scheme.

        Returns:
          True if parameters are set successfully (note that this doesn't mean
          the credentials are valid)
          False if the scheme specified is not supported
        """
        if scheme not in self.schemes:
            return False

        for field, value in iteritems(params):
            setattr(self, field, value)
            if field in self.schemes[scheme][u'params'].keys() and value:
                self.schemes[scheme][u'params'][field] = value

        return True