Switch to final 1.1.0 oslo.config release

Fixes bug #1128256

oslo.config has now been released to PyPI in time for Grizzly RC1 so
we can switch to using it directly.

Change-Id: I655f831718ae5f4e25e941ee206fe195214a9a91
Merge "Switch to final 1.1.0 oslo.config release"