Revert dependency on oslo.config 1.2.0

Fixes bug #1185174

This reverts commit b8b2c4e, 2f13345, 362bd7f, 8da2fb7 and 956b873.

We don't yet have the infrastructure in place to use latest oslo.config
in the gate or even get the correct metadata for it in our packaging.

The gory details are here:

  http://lists.openstack.org/pipermail/openstack-dev/2013-May/009586.html

Change-Id: Idf89ca418df158e6f94279c9c5fa44f23073a9d7
Merge "Revert dependency on oslo.config 1.2.0"