Implement start / stop events for Objects and Arrays

[hubertlepicki]

Similar to Strings, when Jes encounters start of object, i.e. {, it should emit action: start event. When it encounters end of object, i.e. }, it should emit action: stop.

This is so the client code can know when parsing of given item is completed, and object doesn't have any more attributes or array doesn't have any more entries.