Make savanna-db-manage able to discover configs

By passing project to the oslo.config parser, we're enabling several
locations to the list of auto discoverable configs:

* /etc/savanna.conf
* /etc/savanna/savanna.conf
* ~/savanna.conf
* ~/savanna/savanna.conf

Change-Id: I03d112c96c01607bb00f1a86ae8238f3fa4700de
Closes-Bug: #1202227
Merge "Make savanna-db-manage able to discover configs"