CDRIVER-1947 parse JSON containing NIL
CDRIVER-1947 parse JSON containing NIL

ajdavis/libbson,rcsanchez97/libbson,mapr/libbson,mapr/libbson,bjori/libbson,rcsanchez97/libbson,bjori/libbson,mongodb/libbson,bjori/libbson,ajdavis/libbson,mongodb/libbson,mapr/libbson,mongodb/libbson,ajdavis/libbson,rcsanchez97/libbson