Enable setting "config.hidepassed" from URL params

Loading a QUnit test suite with `?hidepassed` appended to the URL is useful for CI services that take a screenshot of the completed test suite upon completion in various browsers, for example.

Fixes #457

/cc @jzaefferer
few whitespace errors:

- space instead of tabs on indentation
- missing spaces before and after arguments list.

@jzaefferer: these should be detected by JSCS, right? If so we can open a issue there.