Updated devstack role to include ORA

1) Adds the ORA role to devstack
2) Creates an ora_env script that activates the virtualenv and sets up other useful environment variables (such as `NLTK_DATA`)

Unfortunately, this will break the Dosa release of devstack because the Dosa Vagrantfile runs only the deploy plays.  Until the next release, you'll need to create the VM from the base Ubuntu image using `configuration/vagrant/devstack`.  You can speed this up by manually updating `configuration/vagrant/devstack` to use the Dosa base image.

I verified that all the tests ran when logged in as `ora`, but I didn't verify that ORA/LMS communicate correctly.

Suggested reviewers: @feanil @stephensanchez