Start using devstack's feature 'Externally Hosted Plugins' [1], that allows
to install Mistral using upstream Devstack without need to put some additional
files manually.
To enable Mistral with Devstack just put following in local[rc] file:
enable_plugin mistral https://github.com/openstack/mistral
[1] http://docs.openstack.org/developer/devstack/plugins.html#externally-hosted-plugins
Implements blueprint devstack-plugin
Change-Id: Ia2f188a6eb369a495a7e0f20534fdd02bafcf49a
junboli