Nepomuk KIO Slave: Clear up all this mess

The Nepomuk KIO Slave is an incredibly simple kio slave that just
redirects to other kio slaves. For such a simple slave it was
unbelievably complex.

It included code from the 4.4 days and had special code for the old
removeable media handling. This commit cleans up most of the code, and
leaves a much simpler easier kio slave.

I don't think I have lost any functionality.