Wrong error message if creating an event when user is not activated

If a user tries to create an event in agenda, an error message displays telling that user is not logged in.

• change error message
• error seems malformed (reason: reason: "api.users.notLoggedIn [api.events.create.notLoggedIn]", message: "api.users.notLoggedIn [api.events.create.notLoggedIn] [undefined]")
• decide if inactive users should have access to calendar