Bug when loading old teaser xmls

Created by: MichaMans

The bug occures if we load an old teaser xml file and it raises an value TypeError in the u_a_calculation. I think i introduced it with commit 8976e322 so i will self-assign it to me and create a new branch and try to solve it.

In addition i will introduce a Unittest for loading the old teaser xmls to avaoid such bugs in the future

• fix bug TypeError
• add Unittest
• fix bug for loadings basic new teaser xmls