Add snarky comment about HHVM in .travis.yml
Change `with()` API to expect a Permutation object

This helps reduce stupid-looking dataprovider-esque permutations.

The old way looked like this:

    $spec->with(
        array("firstarg", "secondarg", "thirdarg"),
        array("firstarg", "secondarg", "thirdarg"),
        array("firstarg", "secondarg", "thirdarg")
    );

The new way looks like this:

    $spec->with(
        data("firstarg", "secondarg", "thirdarg"),
        data("firstarg", "secondarg", "thirdarg"),
        data("firstarg", "secondarg", "thirdarg")
    );

Why is that better? Two reasons.

 1. A permutation object can have a title applied to it via ->title();

    data("arg1", "arg2")->title("when arg1 is first")

 2. It reduces the number of array declarations in a nested
    arg-structure. That's super important given that we're stuck with the
    old (< PHP 5.4) array declaration until 5.3 reaches EOL.
Prepare 0.2.0 release