Add missing stub/skeleton files

[behrtam]

I only worked on the Python and Go track and I noticed a small difference. In the go track (at least for the first 5 problems) there are always stub files, while in the python track there are only stub files for hello-world and bob.
Maybe there shouldn't be stub files for all exercises, but at least for most of them and definitely for the first exercises. It would make the start easier and support TDD, because there wouldn't be ImportError: No module named <exercise> if you try to directly run the tests.

[kytrinyx]

We had a few discussions in the Go track about how many stub files to support, and our answer (a small handful, not too many) was kind of arbitrary, but so far it seems to have worked out.

[behrtam]

I had a closer look into the xgo repo and saw even there only ~20% of the exercises have stub files. If I understand the xruby repo correct they don't have stub files at all.

So, I think this issue should be closed.

[kytrinyx]

Yepp, agreed.