DOC : add note about np.matrix and pandas objects

There is no intentional support for np.matrix or
pandas data objects as input to plotting functions.
DOC : add examples of casting DataFrame and matrix
DOC : slight re-organization of INSTALL
DOC : reorganized/simplified INSTALL
DOC : tweaked text of INSTALL

removed reference to pre-built binaries in source section.
DOC : mention miniconda
Add image tutorial as ipynb - with some additional content
DOC: image tutorial touch-up

- expand some text regarding backend usage and IPython notebook plot
- improve style a bit (PEP 8)
- shorten array printout
- convert image resizing example to use PIL