Add oslo libraries for works with database and config.
Refactor database relation code. Move it in refstack/db.
Now after istallation of refstack available a command-line
utility: `refstack-manage` and `refstack-api`.
`refstack-manage`
This utlity provide commands for manipulation of database
migrations and setup config file through
--config-file /path/to/refstack.conf option.
Config file should contain database connection string.
For example:
[DEFAULT]
sql_connection = mysql://root:passw0rd@127.0.0.1/refstack
Add ability to runtime updrade/downgrade db through command-line utillity.
`refstack-api`
This utility allow to launch api on gunicorn server. Specify config through
--env REFSTACK_OSLO_CONFIG=/path/to/refstack.conf
Change-Id: Ibea97d433d54d307233aa04e9487f1a1230e7487
4e390ee67b