BLD: Set scipy back to 0.12.0

The internal system used to build and get burn-in on packages was
accidentally using scipy 0.12.0, despite the change in the requirements
file to 0.13.2

Setting back to using scipy 0.12.0 until 0.13.2 is more tested with
internal systems, with the goal of upgrading to >= 0.14.0 as soon as
possible.