Allow disabling cache headers in the cache folder's .htaccess

I know it runs counter to the concept of the module however under certain conditions there may be a need to disable any cache control headers (or modify them) issued by the .htaccess coming from the cache storage folder.

When this module is used with CloudFlare's Always Online feature, you can't use the cache deactivating headers which are now assumed by default (using them makes sense because boost has no way to expire a page once cached by the browser however want to keep the site as up to date as possible hence this cache disabling).

My suggestion is to either remove the lines below completely, or to make them configurable (in case of some other use cases this could be helpful):

<FilesMatch "\.(html)(\.gz)?$">
  <IfModule mod_expires.c>
    ExpiresDefault A5
  </IfModule>
  <IfModule mod_headers.c>
    Header set Expires "Sun, 19 Nov 1978 05:00:00 GMT"
    Header unset Last-Modified
    Header append Vary Accept-Encoding
    Header set Cache-Control "no-store, no-cache, must-revalidate, post-check=0, pre-check=0"
  </IfModule>
</FilesMatch>