Issue 187 add proper equals method testing for config

Closes #187.
Sorry for the size of this PR but automated proper testing requires a few lines of code...
Actually I changed this, as the MeanBean framework uses the getters for some comparisons and the equals() method of Collection does not use the proper equals() method of the contained elements for comparison. After talking with @cburkert about that, I changed the getter of this field to return an unmodifiable list and therefore i had to change the type, too. There should not be too big implications.