Use oslo.config 1.2.0

Now that oslo.config 1.2.0 final has been released, projects should stop
requiring the beta version.

Related-Bug: #1182861
Change-Id: Iadbcf27e64a5755e178fc81b5ee225aeb3914026
change pyparsing to >= 2.0.1

cliff 1.4.5 was released and bumped pyparsing min to >= 2.0, which
is beyond global requirements. This has wedged all of the gate,
and no changes will flow until we address this.

Change-Id: I9cfae4bb57f3b9e154d8f044fd36d795e42f7de3
Merge "Use oslo.config 1.2.0"