Set up SauceLabs for browser testing

[phillipskevin]

We ran into an issue where Funcunit was throwing an error on Chrome 58 on Windows 10: canjs/canjs#3235. We should set up SauceLabs testing for funcunit so we can catch these issues earlier.

Setting up SauceLabs is relatively easy using the test-saucelabs package like we are using in canjs here: https://github.com/canjs/canjs/blob/master/test/test-sauce-labs.js.

[morrme]

@phillipskevin can I try this one?

[phillipskevin]

Yeah, definitely. I'll assign it to you, @morrme.

[phillipskevin]

Ok, I can't assign it to you, but it's all yours.