Don't emit empty objects about ksonnet-lib

[hausdorff]

We can close this, because they are necessary, and we will soon have the ability to customize zero-argument constructors when it makes sense.

The reason they are necessary is because the zero-argument new() constructor allows mixins to work. For example, {} + {foo+: "bar"} will work, while {foo+: "bar"} won't.

The reason we can now customize them is largely because of PR #46, which lets us specify new constructors for API objects.