Unit tests for widget.destroy()

[basti1253]

Additionally to #11 we need a unit test covering that issue.

[PizzaBrandon]

If you could describe your build environment to me, I can look into adding the requisite tests for my additions. I don't yet have JS build/test set up on my dev machine.

[basti1253]

We are using qunit for our unit tests. These can be found inside tests/qunit (the html files are our "test cases") and can be executed from any browser. Lint/test/build tasks are available on commandline via https://github.com/coverflowjs/coverflow#installing-grunt.

best regards