Merge db.sqlalchemy from oslo-incubator af5f710

The db.sqlalchemy module was not recent with oslo-incubator.

 $ git checkout af5f71096c7bb83fe2f956588a9ec643b0d9a2f6
 $ python update.py --nodeps --base keystone \
   --dest-dir ../keystone --modules db.sqlalchemy

The af5f710 oslo-incubator db.sqlalchemy contains a fix for the
following problem, which caused a regression in Keystone:

The database connection string was not marked as secret, so it
would be printed out in cleartext in the logs when config settings
were logged.

The database connection string typically contains the password
that's used to connect to the database, so it should be marked as
secret so that it doesn't get logged.

Change-Id: Ibdc63480a836646c5571a368f3c3a1d0c82d6aba
Closes-Bug: #1266590
Merge "Merge db.sqlalchemy from oslo-incubator af5f710"