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.  To install, you'll need to:

a) Remove `ansible.tags = "deploy"` from the `Vagrantfile`
b) Run `vagrant provision`

I verified that all the tests ran when logged in as `ora`, but I didn't verify that ORA/LMS communicate correctly.