Better BrowserView structure

Get rid of skin folder template and use them as actual browserview template, more the plone-way :)
Make actual (sub)classes of the two views (ListUnique and ListAll) instead of attributes, allows us to use the templates.

The functions of both views are almost identical, could combine this further.. by renaming the function and moving it to the super class. Then define a method for each subclass. But that decreases readability.