Reduce jQuery dependencies in tests

[akre54]

I've been experimenting with working around Backbone's (light) jQuery dependency (see #237, scoliosis and others), and it'd be great if the tests had as light a requirement on jQuery-specific features as possible (no more than the library itself does).

• Remove $(document).ready from tests in favor of scripts-at-the-bottom and an IIFE
• Change a jQuery-specific selector p:has(a) to two separate tests

Should make it easier to test with Zepto, adapters for MooTools, d3 and other jQuery-like APIs.

[braddunbar]

Looks good. I like the simplification regardless. Thanks, as always, @akre54!