SampledProperty.setInterpolationOptions does not properly ignore undefined

[shunter]

The implementation does not match the documentation. This makes it impossible to load CZML that relies on the documented defaults for algorithm / degree (LINEAR / 1)

failing test case:

var property = new Cesium.SampledProperty(Number);

var interpolationAlgorithm = property.interpolationAlgorithm;
var interpolationDegree = property.interpolationDegree;

property.setInterpolationOptions({});

expect(property.interpolationAlgorithm).toEqual(interpolationAlgorithm);
expect(property.interpolationDegree).toEqual(interpolationDegree);

[shunter]

Other issues in this class:

• setInterpolationOptions should treat options as optional, as indicated in the doc for the function.
• The example code incorrectly uses backticks for strings instead of single quotes.