Add option to make a file library send an X-Sendfile header instead of the the response body.

[GoogleCodeExporter]

File libraries support support writing their content to disk using 
WAFileLibrary >> #deployFiles. It would be nice if we had an option on file 
library or file handler that instead of sending the content would send 
X-Sendfile header to that or a configurable location.

http://john.guen.in/past/2007/4/17/send_files_faster_with_xsendfile/
https://tn123.org/mod_xsendfile/

Original issue reported on code.google.com by philippe...@gmail.com on 30 Jan 2011 at 6:39