forgot that too...
don't crash if the bson has no data (like bson_init() and bson_finish())
Merge pull request #65 from fotonauts/size_t_64_bits_bis

forgot that too...
CDRIVER-188 Use size_t to follow standard practice (slight API change) 
Merge pull request #66 from fotonauts/do_not_crash_on_release

don't crash if the bson has no data (like bson_init() and bson_finish())
CDRIVER-189
merge from mongodb