Expose the ArtemisSecurityManager methods via TestUtils

[MaisiKoleni]

The ArtemisSecurityManager contains methods required to whitelist threads and manage other security issues, such as proposed in #52. We should use an official class with static method for that which delegates to the methods of the security manager.

It should also be considered to rename TestUtils to something that is more associated with Ares, such as an Ares class.

All of that would improve readability and finding as well as documenting the methods and features that Aresprovides besides the annotations.