Sync db, db.sqlalchemy, gettextutils from oslo-incubator 6ba44fd

This change sync's oslo-incubator's db module from commit hash
6ba44fd7f9d39a7930defb4e14c37b8b1046cbcb

 $ python update.py --nodeps --base keystone \
    --dest-dir ../keystone \
    --modules db,db.sqlalchemy,gettextutils

- Config options were moved from db.sqlalchemy.session to db.options
- db.sqlalchemy.session doesn't provide get_session, get_engine, or
  cleanup functions.
- db.sqlalchemy.migration.db_version() requires an engine parameter

Closes-Bug: #1227321

Change-Id: I742cef9dab68d9eed977df0039736cfe67ca493c