Do not add a Vary header in the ExtDirectSpringUtils.addCacheHeaders method

[ralscha]

The method ExtDirectSpringUtils.addCacheHeaders adds a Vary: Accept-Encoding header to the http response. But if I undersand this correctly the program should only add this header when the response is gzipped.

Most of the servers add a Vary header if they gzip the response. Now what happens is if we enable compression in Tomcat and use the addCacheHeaders method the response contains a weird looking Vary header: Vary:Accept-Encoding,Accept-Encoding

I guess it's best to remove the Vary code from the addCacheHeaders method.