Zuul test report an error for "del"

[cyrilchapon]

I'm getting this :

This seems to be because of beforeEach hook here which does :

    beforeEach(function(done) {
      cleanup(done);
    });

    var cleanup = function(fn) {
      storage.onConnect().then(function() {
        return storage.del('key1', 'key2');
      })
      .then(fn)
      ['catch'](fn);
    };

But in this test-case, storage doesn't have permission to delete.

[cyrilchapon]

Sorry this was created by https://github.com/zendesk/cross-storage/pull/54

I fixed it in the PR.