Fix tests for Plone 5

This makes the tests pass against Plone 5.
Two problems were fixed:

1. `browser.open(obj_path + '/edit')` did not work because `plone.protect` did protect it. There are a lot of places where things like that were done, therefore I've disabled `plone.protect` on the testing layer as quick fix.
2. The folder contents view is different, which broke a copy / paste test. I've changed it so that it does not use folder contents but the copy / paste actions instead.

Related to plone/Products.CMFPlone/issues/223

/cc @tisto
@jone Why do we need c.testcaselayer here? This is a dependency that we would like to get rid of in Plone 5.