For serialization, 64-bit wtimeout values will always be encoded as strings for portability. Debug output and bsonSerialize() can always use integers on 64-bit platforms and can fall back to strings and Int64 objects on 32-bit platforms, respectively.
Note: generic boolean options (e.g. "ssl") will continue to accept non-boolean types for BC, since we cast via bson_iter_as_bool(). However, RP and WC-specific boolean options (e.g. "slaveOk", "journal") will throw since they previously silently ignored non-boolean values.
In addition to revising read preference tests, this adds new tests for read concern and write concern options.
Jeremy Mikola