Get napp_dependencies from install NApp.

        Args:
            user(string)  A Username.
            napp(string): A NApp name.
        Returns:
            napps(list): List with tuples with Username and NApp name.
                         e.g. [('kytos'/'of_core'), ('kytos/of_l2ls')]

def dependencies(self, user=None, napp=None):
        """Get napp_dependencies from install NApp.

        Args:
            user(string)  A Username.
            napp(string): A NApp name.
        Returns:
            napps(list): List with tuples with Username and NApp name.
                         e.g. [('kytos'/'of_core'), ('kytos/of_l2ls')]

        """
        napps = self._get_napp_key('napp_dependencies', user, napp)
        return [tuple(napp.split('/')) for napp in napps]