Don't try to pass shell up kwargs from Magics class

See ipython/traitlets#176 - this is causing test failures.

IPython/core/magic.py

@@ -520,7 +520,6 b' class Magics(Configurable):'
                 shell.configurables.append(self)
             if hasattr(shell, 'config'):
                 kwargs.setdefault('parent', shell)
-            kwargs['shell'] = shell
 
         self.shell = shell
         self.options_table = {}