Use appnope in qt and wx gui support from the terminal; closes #6189

On Mavericks, the qt and wx gui support was unusable from the
ipython console in a terminal.  Using nope() in enable_qt4 and
enable_wx, and reversing with nap() in disable_qt4 and disable_wx,
solves the problem.
I think this wants to be wrapped in a check for OS X 10.9, as in [loop_wx](https://github.com/ipython/ipython/blob/rel-2.2.0/IPython/kernel/zmq/eventloops.py#L74)