Add scripttask type for judgehosts

[vmcj]

Description of the enhancement request

We can currently download debug packages and version commands but it would also be good to be able to run a custom script in the judgehosts. For example to run tasks when you don't have ssh access but also to compare the machines for example. I'm not sure if we also would want an option to either run this inside the chroot or outside.

Ideally we would:

• copy the work done for the debug task
• implement a shelltask type
• Allow a simple sh script to run
• Allow to run this either on 1 host
• or on multiple:
  • and do the diff on the output like we do for normal team output
  • or like shadowing differences between judgehosts