fix bug introduced by 0abd87bd918cb

previosly module_loader.get_module_from_file(nameOnly=True) returned module names
since 0abd87bd918cbd6db20515087aed3a4b651e13f3 this functionality
is handled with module_loader.get_module_name().

This Bug causes an exception at the web frontend show below

Fault at /do_login
<Fault 1: "<type 'exceptions.TypeError'>:cannot marshal <type
'method_descriptor'> objects">