fix precision issue insert NSDecimalNumber
fix precision issue insert NSDecimalNumber

if insert NSDecimalNumber directly into sqlite, it will have precision
issue. so convert it into NSString first

lonelyplanet/FCModel,marcoarment/FCModel,lynns/FCModel,macressler/FCModel,marcoarment/FCModel,iosphere/FCModel,bartekhugo/FCModel,mirion/FCModel,Threadflip/FCModel