Make hasAll work as expected.

$hasAll now checks if all elements of an array are present.
Before, $hasAll did exactly the same as $has.

I wrote a test for it, and had to fix $all, which was dependent on Hash.hasAll, which had a bug. Did this by adding Hash.hasExactly.

I need some help though. I'm new to node.js and docpad. What I can't figure out just jet is how I can use my altered version of query-engine in a local docpad project. It's more difficult than a normal module, since this is a module for docpad itself.