Configuration cleanup: optional options and unneeded lists

Several things here:

• I rewrote the variable parsing a bit so that entries in the "variables" section are checked more carefully: now if someone enters an unused variable type (next to "btagging" or "jet" or "event") the code will error.
• Thanks to this I found (and fixed) some invalid configuration files. I also cleaned up the checker script a bit to give cleaner output.
• I happened to use the kfold unit test to check this and found that it failed. The problem turned out to be a fully specified cvmfs path for the network. We shouldn't use fully specified cvmfs paths, they should all start with BTagging or dev/BTagging, the ATLAS SW takes care of the rest.
• I deleted some unused (at least outside trigger) stuff in the kfold top level script.

Attention @svanstro, @npond