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.
In this test we are just talking about a plain a proxy with currently one `WebElement` after #52 I will change it to `WebElement[]`. 
Just now I get a exception:
`$page->radioGroup->selectOption($page->radioGroup->getValue());`
Which is the same logic like used in `RadioButton::select`. I changed it to `$page->radioGroup->selectOption('1');` which is now working, but I fear that using RadioButton as single element might not work as expected, cause `getValue` will always return the value of a selected radio button, if none is selected in that group `NULL` is returned.