Replace OpenBLAS with Atlas BLAS

[zkamvar]

This is to fix an issue with a segfault caused by OpenBLAS when an incoming matrix becomes over 200x200.

For info on the issue, see rocker-org/rocker#156
Minimum working examples go here: https://github.com/zkamvar/mwe_eigen_segfault

[hlapp]

@zkamvar I've been meaning to document but haven't gotten to it yet - you can generate a build test for your pull request by tagging the branch on which it is with a release tag. The Docker Hub build is set up to build every tag following the /^v[0-9.]+$/ pattern automatically, so if you name the tag accordingly, it will get built. There's no automatic continuous integration badge that signals the status on the PR, so it's a bit crude, but it does work. I've done this now for this branch (see v0.2.5), build is here.

[hlapp]

Builds successfully.