Fix moar

FIX: Make CE2CS agent get a fresh copy of the cs data before attempting to modify it. Closes #1151
FIX: Do not attempt to untar directories before having checked if they are tarfiles. Closes #1161
FIX: Do not create useless backups due to slaves connecting and disconnecting. Fixes #959
FIX: CSVs without end date will be generated now. Closes #288
FIX: Take into account invalid values. Closes #949