Updated openstack/openstack
Project: openstack/requirements  f74d94e4b529102904bf5e63f9d596bb9bf5c797

Updated zake now that zake 0.0.20 is released

The newer zake fixes up watcher usage and makes those work
correctly so that integrating projects can correctly test
that watches are triggered in the correct manner.

This makes it more useful for taskflow & tooz & others that
use this library for testing zookeeper interactions (without
requiring a full zookeeper setup/deployment).

Change-Id: I8973ab25c7b5ad40cf3152df1b43da979ec3c730