Make the test for assignation from XTC smarter
Make the test for assignation from XTC smarter

* The test print PBassign stdout and stderr (the printing is captured by
  nose and actually displayed only if the test fails); this makes
  debugging easier
* The test do not create a temporary directory in the temporary
  directory created by the SetUp anymore

pierrepo/PBxplore,HubLot/PBxplore,pierrepo/PBxplore,jbarnoud/PBxplore,jbarnoud/PBxplore,HubLot/PBxplore