Release Display properly

With the latest fixes to amira and the gpu display, there's a new issue due to the VNC server not releasing the display when the container is shutdown. This causes an error when multiple users try to use the tool. This is likely due to the way we stop the container and whatever seg signal isn't getting caught to gracefully stop.

Need to catch the seg signal, and stop everything gracefuly. If the display still doesn't get released then release it manually by removing the tmp file in /tmp/.X11-lock. Additionally, the tool should check which displays are currently in use and pick a free one.