The problem was with my wife. She was using my MBP for some time and deleted some files accidentally. Unfortunately my settings.xml was deleted and in the settings.xml I had all my repository definitions. I have them back now and it seems to work!
SCJP 1.4, SCWCD 1.4 - Hints for you, Certified Scrum Master
Did a rm -R / to find out that I lost my entire Linux installation!