Restricting users from accessing parts of different sites

[Kabir Khan]

I have a requirement to restrict one of our django sites on open edx to only logged in users.

I have developed a middleware class for this and I'm wondering if anybody else has similar requirements 

and if this is something that could be contributed back to the edx-platform.

The change allows you to flag a site as restricted through the site_configuration table and is set to False by default.

Take a look at the changes if you're interested: https://github.com/Microsoft/edx-platform/pull/25/files