Make the Cover object to be an Item instead of a Container. Fixes #114
In order to be able to load dexterity items from the import content GS step, we need to provide this interface manualy, until a proper fix in dexterity is implemented.
Have the <base> tag to include a slash at the end so relative ajax calls are called for the object and not its parent. fixes #48
Add test.
Merge pull request #135 from collective/114

closes 48 and closes 114