mod_http_oauth2: Add Cache-Control and Pragma headers per by RFC 6749 These are mostly for the various Client-facing endpoints, so the chance of browsers being involved is slightly lower than with the User-facing authorization endpoint, which already sent the Cache-Control header. Thanks to OAuch for pointing out.

--% conflicts: mod_bookmarks
module:log("info", "mod_bookmarks has been deprecated, now loading mod_bookmarks2")
module:depends("bookmarks2")