Remove reference to more_headers module (#3323)

These references are leftovers and are not used anymore.

Author: jmelis

nginx.conf

@@ -65,13 +65,11 @@ http {
             try_files $uri $uri/ @conbackend;
             etag off;
             if_modified_since off;
-            more_clear_headers 'Last-Modified';
         }
 
         location /_openshiftio/ {
           etag off;
           if_modified_since off;
-          more_clear_headers 'Last-Modified';
           expires 1y;
         }