Check for fields being empty or null before including projection

With the updated projection login in mongoconnector it no longer has the functionality to by default export all fields from the target mongo instance to the destination.  Instead the default will cause fields to be an empty array and when passed into the find methods mongo will then show no fields except for _id which is in every entry unless explicitly removed in the projection.  I added some logic to catch these empty / null field values and default to getting all fields from mongo.