Decorator to convert dbus exception to pympris exception.

def exception_wrapper(f):
    """Decorator to convert dbus exception to pympris exception."""
    @wraps(f)
    def wrapper(*args, **kwds):
        try:
            return f(*args, **kwds)
        except dbus.exceptions.DBusException as err:
            _args = err.args
            raise PyMPRISException(*_args)
    return wrapper