Remove "kuksa.val" from files

[erikbosch]

We still have quite many references using the term kuksa.val and also referring to old deprecated kuksa.val repositories. We should better do a search in source code and try to replace all instances of kuksa.val with something else.

[erikbosch]

Will be mostly fixed by #83.

What we might need to discuss (FYI: @SebastianSchildt ) is what to do with old blog posts. I have generally avoided to touch them unless links are permanently broken (and could be removed without making the blogpost useless), but what policy do we want to have, i.e. when shall we remove a blog post.