Add format as a parameter to Lookup method

[Skylude]

This way we can specify if we want xml/json/text etc.

[Zaidos]

Hey @Skylude, great idea. I can start working on this, unless you have already started.

Also, with this change, I propose that we move away from a static interface to an instance of the OpenCNAM class. That would make it easier to specify API parameters, like in this case.

[Skylude]

@Zaidos sorry I've been a bit busy. I made a few alterations but nothing huge. If you want me to make any of the changes let me know.