more "post-release" work for https frontend

the /howto, /maintenance, and /info endpoints are still using the old mako templates instead of the new lektor-generated pages. I don't believe they were ever part of the ticket to move to the new lektor frontend.

They're pretty basic pages, so they shouldn't need much more than creating a page with the basic layout and content.

this ticket was originally just for those three pages, but @nicob pointed out more changes needed in this thread