Consider HTTPS instead of only HTTP

[grdryn]

As mentioned in this discussion on discourse, Fedora Planet currently doesn't support HTTPS at all.

This migration effort would seem like a good time to consider addressing that. Kevin points out that all of the aggregated feeds would need to support HTTPS to do that. If the ini files here are going to be the source of truth rather than the per-user files in fedora people home directories, then it should be fairly straightforward to do it here I think.