Added tests for pages via Mink

This tests the whole library and pages without mocking via Mink and the Selenium Driver.
Just now only basic but we can improve them and add more later.
Are you sure, that you've pushed the changes? I'm seeing old code here.

There is a dilemma what is `test` and what is `test case`. I consider the `test` to a file, that ends with `Test.php` and `test case` to be a method in that file that starts with `test`. However this might be otherwise in reality. Google doesn't say much on a subject either.

I'm telling that because when I meant `in this test` I though in this class and all test cases in it. I mean to replace the xpath with a constant.