api info reports also the python version #40

testlinkapigeneric.__str__ prompts now the python version as additional
info

minor additional enhancement for test and example, which works with text
file attachments: replace 
  *os.path.realpath(__file__)*
with 
  *os.path.join(os.path.dirname(__file__),fname.py*
cause __file__ could be a compiled python file *.pyc, if the test run is
repeated without changing the test code