Make tests pass with Zepto

After doing a little bit more digging for #2431, I was able to get the test suite to pass with the latest version of Zepto.

Zepto does not support triggering events for elements that aren't in the DOM. I changed the few instances in the test suite where we were triggering events on views that aren't in the DOM to add themselves to `#qunit-fixtures` and voila, the test suite passes in Zepto.

I went ahead and added the Zepto tests to the travis build, too.

Seeing that we still recommend that it's a valid jQuery replacement, I think that we should keep the tests for it or either alter the docs to say explicitly that we don't support it.