attempt to fix regression introduced in #706

IE doesn't like loading https JSON for http pages

@defbyte we got a support request from someone who was apparently a beneficiary of the behavior removed in #706.

I implemented something that just makes the URLs protocol relative instead of rewriting them, and it works in my IEVM test environment (Win 7/IE 9)

Could you do me the favor of checking it in your environment before I merge this?