sync oslo db/sqlalchemy module

sync oslo db/sqlalchemy module to grab "Mark sql_connection with secret
flag" change.

fixes bug 1160680

Change-Id: Id48419624c41eea5a0f2e130d7cdbe8a8f0a9118
(cherry picked from commit 6ff9c9effe011cb7d8d5479ec8cd2f6c7f61705c)
Merge "sync oslo db/sqlalchemy module" into stable/grizzly