Merge r504183 from trunk:

* Add CacheIgnoreQueryString directive to cache requests with a query string
  even if no expiration time is specified. Futhermore the query string will not
  be used for key generation such that requests to the same URI path, but with
  different query strings are mapped to the same cache entity. Turning this
  setting to ON violates RFC 2616/13.9 and thus it is turned off by default.

PR: 41484
Submitted by: Fredrik Widlund <fredrik.widlund qbrick.com>
Reviewed by: rpluem, jerenkrantz, jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@539111 13f79535-47bb-0310-9956-ffa450edef68