Fixes for qt apps related to selection and re-calling use()

Pyglet was higher in the list then PySide and PyQt4, making it
be selected earlier if both pyglet and PySide were in sys.modules.

repeatedly calling app.use() with 'PySide' or 'Qt' did not work
because the backend name is something like 'PySide (qt)'.
Null commit to trigger Travis

Test whether the qt segfault is reproducable or a glitch
Use faulthandler when running nose tests

For our lovely segfaults :)
FIX: Fix segfaults
FIX: Revert Qt changes