Added Bluebird versions of addFact, getFacts, getAllSeenKanji, getAllSeenWords
Added Bluebird versions of addFact, getFacts, getAllSeenKanji, getAllSeenWords

Also added in `handleError` helper function.

ianhenderson/kstool,ianhenderson/kstool,ianhenderson/factly,ianhenderson/factly,ianhenderson/factly,ianhenderson/kstool