Part 1: Fix for images disappearing in tenant mode

This is the first of three commits which will fix the images disappearing in the Publisher and Store when in and out of tenant mode.

In this commit the storage.security.provider has been moved from the application context to the session.

This will prevent the images from disappearing after logging out of a tenant .

Todo:

Part 2 :Implement changes in Store
Part 3: Consider anonymous access