remove pficommon dependancy
Use jubatus.common.Datum instead of types.Datum
Add preprocess
Merge pull request #23 from unnonouno/preprocess

Add preprocess
Merge pull request #22 from unnonouno/use-common-datum

Use jubatus.common.Datum instead of types.Datum
Merge pull request #20 from odasatoshi/fix_remove_pficommon

remove pficommon dependency