Use bobtail repo

Crowbar's barclamp-ceph recipes are being updated for bobtail and
cuttlefish. Adding bobtail repo instead of pointing to argonaut.

Signed-off-by: JuanJose 'JJ' Galvez <juanjose.galvez@inktank.com>
Remove unused ubuntu versions

Crowbar installs ubuntu precise these other repos would not be used.

Signed-off-by: JuanJose 'JJ' Galvez <juanjose.galvez@inktank.com>