Cvm 617

Removes CERN specific configuration from cvmfs package.  The configuration and public keys are provided in cvmfs-config-... packages.  The cvmfs-config-cern package replaces cvmfs-keys and cvmfs-init-scripts.
Do you want to set a CVMFS_CONFIG_REPOSITORY here?  It would have implications, because it implies a support model that may make CERN stuck supporting configurations for everybody.  Maybe it's better to leave that to egi.eu and opensciencegrid.org.  Leaving them out of cvmfs-config-cern will kind of encourage people to upgrade to the configuration rpms of those organizations.