Use shallow clone from GitHub instead of copying local tree
Use shallow clone from GitHub instead of copying local tree

We cannot use COPY since the user may have attempted to build mcjoin
locally first, in which case config.status may likely be incompatible
with our Alpine system.

Also, this makes the Dockerfile more stand-alone.

Signed-off-by: Joachim Nilsson <583c295fd7602c168ad814279bbc3894ba65f5d6@gmail.com>

troglobit/mcjoin,troglobit/mcjoin