Add egi.eu and opensciencegrid.org to cvmfs-keys

Moves cern.ch.conf to cvmfs-keys and adds egi.eu and opensciencegrid.org configurations.  The latter do a temporary automatic server ordering that we can use prior to the next release of the cvmfs client.  That is, we'll be able to release cvmfs-keys earlier, and it will work with all versions of cvmfs client.  The two new domains will be hosted on 5 stratum 1s as cern.ch is, except the CERN stratum 1 is replaced by NIKHEF's stratum 1; I contacted all involved and they have agreed.

Also removes the dependency of cvmfs-keys on the cvmfs package  for both rpm and debian, and instead makes them conflict with cvmfs-keys versions older than this new one cvmfs-keys-1.5.  The Mac cvmfs package just includes all the cvmfs-keys stuff for now.  I'm not sure that's the right thing to do.  We may want to split that into two packages as well later.

I tested all 3 packaging styles.