added tests to remove the superclass of classes
put SuperclassMismatchChange into own file
superclass mismatch now gives string with new superclass
change_superclass_to now replaced remove_superclass
migrations work if superclass change classes are not existent eny more
persisted the class method taht caused the error on trovis
maglev_record does not commit any more in require
always making ActiveSupport::Errors nil references
Merge remote-tracking branch 'origin/develop' into niccokunzmann/migration