Tests: Change the assertion lib to unexpected?

[papandreou]

This is the nicest assertion library I've worked with so far: https://github.com/sunesimonsen/unexpected

If no one objects, I'll happily do the job.

[sunesimonsen]

Thanks @papandreou - that is a very nice compliment :-)

[papandreou]

Yeah, please take it as one. And you know I'm being sincere, because I've already started using it in a bunch of projects :)

[msiebuhr]

Go for it!