Allow to access BinData binary value from MR

Synopsis: please add BinData.getBytes() to be able to deal with BinData value easily from MR

Currently the only way to access the value from a BinData object in your javascript map/reduce job seems to call base64() and decode the value using a custom js function. This is especially inconvenient in cases where you have certain fields packed in your _id (such as customerId, year, month, day in my case) and want to mask out parts of the _id to derive a new key for MR. This would be really easy to do if there was a BinData.getBytes() function returning an array of numbers.