Image tutorial notebook edit

Make the Image tutorial more friendly to people using the IPython notebook to follow along (avoid use of set_xxx functions, use arguments to imshow instead.)

Also:
- use scipy.ndimage for image resizing in last example (interpolation)
- minor grammar fixes
- add notes about keeping plt commands in one cell so that effects are shown.
I would also vote for only mentioning the %matplotlib magic and not including the flag at all. 

My understanding is that IPython will only allow the flag in the consoles and not the notebook from version 3.0 due to the reproducibility issue. The reproducibility is much less of an issue for the console. (the same will be true for for --pylab and --matplotlib)