Allow for whole versions to be deprecated and end-of-lifed in read the docs

As we move versions of OpenDaylight to security-only patches and then unsupported, we should actively flag that fact in the docs for that version on all pages.

For example Django docs look like this for insecure versions:
https://docs.djangoproject.com/en/1.7/

And this for versions under development:
https://docs.djangoproject.com/en/dev/