New API propagation?

[JoelBender]

The Application class has new parsing routines to make it easier to translate strings like device,123 into an ObjectIdentifier. These are used in the read_property() methods so library users don't need need as much boiler plate code and it can consistently handle proprietary object types and properties. A "strong" and "type safe" API would restrict the address parameter to be an Address instance, so I'm putting this in the Robustness Principle.

I made changes to the read-property.py sample applications, but not to do_read() in __main__.py, so the down side is that there is more than one way to call the API.