Add Spring Security Layer

[eeebbaandersson]

This issue should perhaps be broken down into several sub-issues:

• Login-page —> Username/password
• Add authority/role based access

[eeebbaandersson]

This issue should also extend to update and secure the Visa & Comment part of the application.
To make sure we remove the currentUserId that now is sent as @RequestParam in VisaViewController for example