Add support for all formats defined in the latest version of the MongoDB extended JSON spec:

http://docs.mongodb.org/manual/reference/mongodb-extended-json/

For example, the following is not yet supported:

{ d : { $date : { $numberLong : "1234" } } }

Go through the spec and verify that all defined formats are supported. Add any missing unit tests.

This ticket is for reading only. There will be no change to the output formats for now.