Upgrade OpenBLAS to 2.8.

This also removes the download of Lapack since OpenBlas now ships lapack
as part of the tar file and repo see
https://github.com/xianyi/OpenBLAS/blob/master/Changelog.txt

This also separates the tests for easier inspection.

This is a slight improvement over https://github.com/Homebrew/homebrew-science/pull/316