Updated openstack/openstack
Project: openstack/requirements  986447a4edbc15f97104189cdc67780430a51bae

Update oslo.config to 1.4.0.0a2

oslo.config 1.4.0.0a1 has the config fixture which Keystone can
use.

1.4.0.0a2 has the config generator which Glance and Nova will
adopt, and cfgfilter which oslo.messaging wants to adopt.

Change-Id: I6c3049e6e379c83af7e6e7df8855b1a6c0b698e7