Update for the new support page infrastructure.

This updates Review Board to work with the new support infrastructure
being deployed on our servers.

rb-site now asks for a Company name, which can also be provided later on
the General Settings page. This name will show up on the support page
when users visit it. We may also want to use this down the road to help
brand Review Board itself.

rb-site will also ask for permission to collect support data, and
explain what we collect and how it's used. This can be changed later
through a checkbox on the Support Settings page. If allowed, rb-site
will up and maintain the support page on install and upgrade.

Reviewed at https://reviews.reviewboard.org/r/6015/
Point users to Power Pack and support contracts after a site install.

After a user installs a site with 'rb-site install', they're now given
links to Power Pack and to our support contracts page. These are
benefits that we historically haven't done a great job pointing new
users to, so we want them to at least know about them as they're getting
going.

We even make the Power Pack trial process a bit easier by giving users
their install key up-front.

Reviewed at https://reviews.reviewboard.org/r/6020/
Include the Python version in the support tracking data.

The Python version is now sent along with the other support data, in
order to better track issues and see what versions of Python are still
being in use.

Reviewed at https://reviews.reviewboard.org/r/6038/