ATLAS: Higgs Challenge 2014 software record update

* Updates ATLAS Higgs Challenge 2014 software record with link to GitHub
  repository.  Archives latest "v0.0" version.  (addresses #660)

* Removes second software record, since there will be only one software
  repository for now.

* Improves indentation of the MARCXML file.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>