lock html5 to version 0.3.13 as 0.3.15 breaks zombie

The dependency on the npm module html5 is breaking zombie. The floating patch level increase (~0.3.13) is breaking zombie. The latest version of html5 is 0.3.15 and breaks finding DOM elements in the HTML.

The simple test that used to work below no longer works with html5 0.3.15.

it("has a title", function (done) {
async.waterfall(
[
function (next) {
browser.visit(server.url() + "/", next);
},
function (next) {
expect(browser.text("title")).to.equal(
"welcome");
return next();
}
],
done
);
});