Create a basic Satie instance when calling Satie.new without args

Currently, we need to provide Satie.new with an instance of SatieConfiguration in order for a Satie to be created. A nice thing about SatieConfiguration is that it can be create with just its default values. This means SatieConfiguration.new() can create a basic object but Satie.new() cannot.

We should provide default arguments to Satie.new(). A nil value for argument satieConfig should create a default SatieConfiguration.

This MR adds a new test TestSatie which is useful for testing the Satie class without needed the server. I also improved the documentation for Satie.new and Satie.config.