Matches Header Names Case Insensitively

[ncronquist]

• It doesn't look like this extension is being maintained anymore, but I added a small fix for myself and figured I would offer it upstream
• For anyone else here who doesn't own the extension in the chrome store, please note that it appears the chrome store extension is based off the dev branch of this repo
• The extension was matching the response rule header names exactly rather than ignoring the case and that was causing the * scoped origin header to be appended to nothing (with a comma) instead of replacing nothing