ENH: don't solve linear system twice in a row
BUG: numpy broadcasting error in asset pricing
Merge pull request #7 from spencerlyon2/minor_fix

ENH: don't solve linear system twice in a row
Merge pull request #8 from spencerlyon2/asset-pricing-bug

BUG: numpy broadcasting error in asset pricing
BUG: fixed bug in asset pricing solutions

we were trying to verify that the computed v was a fixed point of
the value function, but we were using the wrong equation.

All I needed to do was swap a `-` for a `+`.