2.12.0

Cloudflare

• Added Cloudflare ProxyClient Adapter with ClearCapable, PurgeCapable and
  TagCapable. This allows to use FOSHttpCache to invalidate caches on
  Cloudflare. See the "Proxy Client" section of the documentation for how to
  configure the Cloudflare client.

Varnish Cache

• Added a fos_user_context_hash method to be called in vcl_hash when using the user context
  hash mechanism. This can avoid performance problems Varnish can run into when the hash Varys on
  the basic authentication or session cookie.
  If you use the user context, read the updated documentation and call fos_user_context_hash in
  your vcl_hash function.

Noop Client

• Implemented ClearCapable.