pandas.stats.ols.MovingOLS._calc_betas incompatibility issue with newer numpy
numpy version 1.8.2
pandas version 0.14.1

In pandas/stats/ols.py:821, we have:
        mask = -np.isnan(betas).any(axis=1)

This causes problem with newer numpy which deprecated negative unary operator (-) on boolean arrays. I got this following error when running into this line:
DeprecationWarning: numpy boolean negative (the unary `-` operator) is deprecated, use the bitwise_xor (the `^` operator) or the logical_xor function instead.

When I change "-" to "~", the problem goes away. It's minor, but hope we can incorporate this into next pandas update.  Thanks.
