Synchronized with oslo db code

File openstack/common/db/options.py was NOT included

List of changes:

b3fbddd Drop dependency on log from oslo db code (on review)
c521705 Make wrap_db_error() a class decorator (on review)
64e87f2 Don't use cfg.CONF in oslo.db (on review)
9da4274 Don't store engine instances in oslo.db (on review)
39e1c5c Move db tests base.py to common code (master)
9a203e6 Use dialect rather than a particular DB API driver
1779029 Move helper DB functions to db.sqlalchemy.utils
bcf6d5e Small edits on help strings
ae01e9a Transition from migrate to alembic
70ebb19 Fix mocking of utcnow() for model datetime cols
7aa94df Add a db check for CHARSET=utf8
aff0171 Remove "vim: tabstop=4 shiftwidth=4 softtabstop=4" from headers
Merge pull request #3 from malor/sync-31-01-14

Synchronized with oslo db code from 39e1c5c