Added first Jest test (including Jest setup)

We really need JavaScript tests for this component, and Jest was the first toolkit that came to mind. I'll also try to workout a pull request for at least one other tool (maybe karma), so we can compare the pro's and con's.
Not needed in this pull request
No reason to run on two versions of node.

Even more so: Node 0.11 doesn't seem to be willing to run our tests. Probably not compatible with Jest or whatever.
Updated README
Merge branch 'jest'

Conflicts:
	package.json