check sucessful statistics counters readout
detaching of old catalog structure after migration + hard fail behavior
append 'C' to migrated catalogs in CAS
allow the user to disable data chunk checking in 'cvmfs_server check'
Merge branch 'disable_data_chunk_checks' into migrate_legacy
Merge pull request #115 from reneme/disable_data_chunk_checks

Optionally disable data chunk checking in cvmfs_server
Merge branch 'master' into migrate_legacy