descriptor: introduce Print method for logging
descriptor: introduce Print method for logging

hustbill/goleveldb,FactomProject/goleveldb,rentongzhang/goleveldb,no2key/goleveldb,zzl0/goleveldb,btcsuite/goleveldb,chai2010/goleveldb,conseweb/goleveldb,ngaut/goleveldb,trigrass2/goleveldb,syndtr/goleveldb