Replicape Beaglebone T slot mount with better accessibility

This is T-Slot mount for beaglebone, designed specifically for a replicape controller board, but would work for many other beaglebone mounting applications. It is similar to the other versions listed as sources, but I changed it to have the board extended out for better accessibility to the connectors when mounted in a delta printer base. I also elevated the standoffs for the beagleboard so that mini-usb and ethernet connector are usable above the 20x20 extrusion that it is mounted to. I didn't