Installs a replacement for sys.excepthook, which handles pretty-printing uncaught exceptions.

def _install_exception_handler(self):
        """
        Installs a replacement for sys.excepthook, which handles pretty-printing uncaught exceptions.
        """
        def handler(t, value, traceback):
            if self.args.verbose:
                sys.__excepthook__(t, value, traceback)
            else:
                sys.stderr.write('%s\n' % unicode(value).encode('utf-8'))

        sys.excepthook = handler