Paper: Validated numerics in Python with ValidiP (David Sanders)

This is David Sanders's contribution to the SciPy 2014 proceedings: Validated numerics in Python with `ValidiPy`

Now ready for review.
t might be good to give reference to AD, both in general computation and also within the Python ecosystem.

Also, there is the reference to derivatives in the Interval Newton method the connection between this section and the others is fairly loose.  

It would be nice to see some simple example of using automatic differentiation and interval arithmetic together and show how its useful over, say, the combination of interval arithmetic and finite differences.  I imagine that, working safely, using FD expands the interval quite a bit more quickly than using AD.  A plot showing divergence over time between the two methods would be illustrative.