Add WebDriver Test on box api market place

The default test is login/logout which actually doesn't test at all the api.

It should actually be very easy to check that we get something at a given api url in web driver to make sure the package is correctly installed.

Indeed, we had a couple of issue with http://qa.nuxeo.org/jenkins/job/addons_FT_nuxeo-box-api-master/ and it took a while before we figure out that the package was actually not correctly installed.