WIP For Initial Review: Feature/cdodge/alpha microsite

This feature is to support domain branding (e.g. 'foo.edx.org') as required for some B2B launches soon (mid-January).

I wanted to get together a pull request so that some people can start taking a look at the diffs. In particular, @sefk can someone from Stanford look at this and make sure it'll be compatible with your theming.

Test writing is TBD, but wanted to get some eyeballs on this main implementation.