Add fdupes command

[iemejia]

Based on the idea of:
https://github.com/seabre/finddupes/blob/master/finddupes.sh
SELECT hash, location FROM files WHERE hash NOT IN (SELECT hash FROM files GROUP BY hash HAVING ( COUNT(hash) = 1 )

[iemejia]

or fdupes https://code.google.com/p/fdupes/

[iemejia]

what to do with hardlinks ?
--gen-rm-script catalog: to generete a script to remove the dupes in the specific catalog

[iemejia]

The query is:
SELECT hash, path, name FROM catalog WHERE hash NOT IN (SELECT hash FROM catalog GROUP BY hash HAVING ( COUNT(hash) = 1 )) order by hash;