BUGFIX: Added X-Forwarded-Protocol and User-Agent to Vary header.
NEW: Improve HTTP caching logic to automatically disable caching for requests that use the session.

This improvement makes it easier to set a side-wide default cache time without needing to worry about CSRF-protected forms, etc.
FIX: Fix issue with not being able to log out on Chrome when caching enabled because of Chrome bug
Merge pull request #1080 from sminnee/caching-improvements

Caching improvements