issue #2 and issue #6 resolved

- if the new keyword is not used to construct an object then Rhino doesn't set the parent scope or prototype for said object... implemented workaround where a threadlocal stores the currently executing Context's associated MongoScope and if any property is accessed via a ScriptableMongoObject a check is made if prototype or parent scope exist... setting the appropriate values if none are found
- adding explicit test coverage for constructing mongodb objects without the new keyword