[Box-Admins] Added a Jenkins job for tracing a 64-bit image

I added one more Jenkins job called "Squeak 64-bit image". This will hopefully be triggered each time the SqueakTrunk job runs. The output is a copy of the trunk image traced to 64-bit object format.

I want to see this run for a few days before I mention it on the squeak-dev list, but I think that this will give us an easy way to maintain a 64-bit version of released images.

The build script is actually pretty cool, if you don't mind me saying so. It used to take a lot of manual steps to trace an image to 64 bits and clean up the resulting image to make it look like the original. But this script automates the process with no cleanup required :) The script is here:

http://squeakci.org/job/Squeak%2064-bit%20image/ws/TraceTo64.st

Dave