Support replay with iFrame being used to display OpenWayback header

[kris-sigur]

JavaScript injection is used to display the existing OpenWayback header that allows navigation in time and provides information about the current resource. This only works for HTML pages and even then, only some times.

Adding a way of accomplishing this with a page that displays the archived resource in an iFrame would allow non-HTML resources to have this header.

It should be configurable whether HTML resources use the new iFrame header or the existing JS injection header. Possibly this should be overridable based on some rules?