Reverts HEAD request back to a GET (#822)
Reverts HEAD request back to a GET (#822)

Looks like MDN blocks HEAD requests. So we're going to revert back to
GET to make sure we don't get any false negatives.
mozilla-mobile/focus,justindarc/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus-ios,mozilla/focus,justindarc/focus,mozilla-mobile/focus,mozilla/focus,mozilla-mobile/focus-ios,mozilla/focus,justindarc/focus,mozilla-mobile/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus-ios,mozilla-mobile/focus,justindarc/focus,mozilla/focus,justindarc/focus,mozilla/focus,mozilla-mobile/focus-ios,mozilla-mobile/focus,mozilla-mobile/focus,justindarc/focus