Fix mod_esi timeout response

[Bernard Duggan]

When a mod_esi operation times out, the response header it generates is 
invalid:

HTTP/1.1 {504,[84,105,109,111,117,116]} Internal Server Error

This patch fixes it so that the response is correct:

HTTP/1.1 504 Gateway Time-out

Assuming I got the git stuff right this time, you should be able to grab 
it here:

git fetch git://github.com/bernardd/otp.git mod_esi_timeout_fix

Cheers,

Bernard