Add browser test for manage_categories view.
Rebuild logic behind manage_categories view:

Don't search for categories to list downwards from shop root, but instead upwards
from current context. This will only return contiguous shop category structures,
and should therefore work nicely for setups with decentralized shop structures.
Preemptively bump version to 2.0 because of major functionality changes.
Eliminate all uses of the IShopRoot interface.

Instead we use the navigation root to register views
that are supposed to be shop-global. This will make
ftw.shop work with subsites that are supposed to
have "their own shop".
BugFix: If the fullname of a logged in user had umlauts the form was broken.
BugFix: It's possible to have users wihtout a fullname: For example SystemUsers / ldap users.
Merge pull request #22 from 4teamwork/lg-eliminate-shop-root

Eliminate all uses of IShopRoot interface