[WIP] New pygraphviz recipe

[nividic]

Try to build pygraphviz

[Lnaden]

I would hold off on merging this for just a bit (this morning, 7/21/17), I am about to merge the #761 which will change the docker build image. We will require conda-forge as a channel after that PR along with omnia, so the install instructions will change.

We also encourage migrating packages over to conda-forge after that as well, so it might be worth trying to build the package there instead.

[Lnaden]

This PR is having issues building, missing things like coverage and toolchain (which I think is conda-forge only). We won't be able to merge the PR which makes this conda-forge ready (#761) until OpenMM patch 7.1.1 is ready. I don't have an exact timeline, but it should not be too long. We have merged the dev version of the conda-forge PR and so far things look good.

If you can fix this PR without conda-forge requirements before we get the 7.1.1 patch for OpenMM in, feel free to merge this.

The toolchain from conda forge is basically just a bunch of sym links and environment variables, so it should be possible to build without it, but then the build.sh script will be different.