Revert "if we dont get a response code, send a 504 instead of a 200 for the case of server down"

Found some cases where PhantomJS doesn't call onResourceReceived with the status code for the original URL.

Going to investigate more before changing this.

This reverts commit d31e138ca72322e06b7e3c62f2614ffc84c48e57.
bumped version to 3.3.17