Add config option to force redirect to HTTPS

Replace: https://github.com/hipache/hipache/pull/161

Please, let me know how to add a (functional) test case for such a feature. I'd like to setup a new server with a new configuration file, so that it won't affect existing test cases.
So, what happens with host names that would contain the port? And yeah, numerals in hostnames exist :-) `37signals.com`