Changes vecLib.framework location for OSX 10.9 and 10.10

Starting in OSX 10.9, Apple has moved the vecLib framework under
the Accelerate framework. This patch accounts for that change
in the setup.py. Without this patch, it is difficult to build the package
using pip.

See Apple's developer documentation for details:
https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man7/Accelerate.7.html