Correct base class of no_conf driver

1. Fix wrong base class of no_conf store driver.
2. Enhance create_stores() to handle NotImplementedError case.

Change-Id: I0f38d101a994b3a3d0c7a10bdd2e936e026b407b
Signed-off-by: Zhi Yan Liu <zhiyanl@cn.ibm.com>
Merge "Correct base class of no_conf driver"