Refactor Team class

Make the constructor explicit and drop the Team_id comparisn operators
in favor of the operator Team_id().

Signed-off-by: Jan Losinski <losinski@wh2.tu-dresden.de>
Add a helper library to the libmue unittests

Signed-off-by: Jan Losinski <losinski@wh2.tu-dresden.de>
more Teams unittests

Signed-off-by: Jan Losinski <losinski@wh2.tu-dresden.de>