Record testcase directory in judging runs.

[meisterT]

This makes it much easier to find out where to go for debugging.

Fixes #2059.

Example:

Clicking the copy/paste icon copies the full path.

[meisterT]

This is an alternative to #2211

[vmcj]

Fine by me, lets see which one @eldering wants.

[eldering]

Fine by me, lets see which one @eldering wants.

I think this solution is better than #2211 : both in the place/way the information is displayed and also by taking the actual directory from the judgehost instead of depending on configure/build time variables.