Allow empty labels, move state CSS class to outer div.

[adamdicarlo]

@cgarvis how do these changes look?

• Allow empty labels: See the new tests, which fail on the existing code
• Template change: This allows more styling flexibility. Specifically, I did this so I could color the main outline red or green depending on whether it's off or on. It's a lot easier to put the border on the outer element.
• Updated the build (btw I think it was already out of date).

[adamdicarlo]

I'd suggest bumping major version if you merge this, due to the CSS change.

[adamdicarlo]

Ah, did you want me to remove the "Update build" commit from this PR?

[cgarvis]

Yeah don't have the build commit. I do that on a release on github. That way the built js is what is stable.

[adamdicarlo]

(Will re-push without the 'Update build' commit tomorrow)

[adamdicarlo]

Re-pushed without the Update build commit.

[adamdicarlo]

Is this merge worthy? Anything I can do to clean it up?