Revert "Add a 'leaf' class to menu nodes if they don't have any visible"

This reverts commit 3d4af44bed210be3af5f46e73d2650786fc90059.
Use Django 1.5.1 for travis config and test project
Merge pull request #178 from mbraak/django_1.5.1

Use Django 1.5.1 for travis config and test project
Updated exterenal packages to the latest stable releases.
Extend Fiber's Permission class with a new method, that checks if a user  is allowed to see the Fiber admin interface.
Only evaluate request's user attribute in the middleware if it exists.