Fix page not being cached X-Session
Fix page not being cached X-Session

Also retain the ability to prevent warnings being fired due to un-initialised constants. This was added previously.

Note that this actually reverts changes made in #346 but without re-introducing the warnings that were previously observed.

tgaff/site_prism,natritmeyer/site_prism,natritmeyer/site_prism,tgaff/site_prism