SSL support needs tweaks

[odscjames]

This tools now indexes a site that is available on both HTTP and HTTPS; in the future this site will hopefully be available on HTTPS only.

Firstly, in doing #4 we decieded the base_url in the data store would always be HTTP. If an incoming search request comes in with a HTTPS base_url, we'll just rewrite this to HTTP.

The second part of this is that we must make sure the indexer will always save records to the data store with a HTTP base_url.

There is also another issue; should the URL in each search result be HTTP or HTTPS? If would be nice if it was HTTPS, so a user clicking on a result goes straight there with no possibility of hijack, but we need to make sure HTTPS will definitely stay on first.

We might need to do this before turning on full SSL - see open-contracting/standard#878 for that work