Added a package for the MDAnalysis toolkit. (#3576)

* Added a package for the MDAnalysis toolkit.

* Added the dependency on setuptools.

* Added the rest of the dependencies to the py-mdanalysis package.  Also
added the griddataformats and seaborn packages to satisfy requirements.

* Removed seaborn package since it has been recently added.

* Fixed flake8 error

* Removed inadvertent commits.

* Cleaned up reviewers feedback.

var/spack/repos/builtin/packages/elemental/package.py

@@ -68,6 +68,7 @@ class Elemental(CMakePackage):
     # Hack to forward variant to openblas package
     # Allow Elemental to build internally when using 8-byte ints
     depends_on('openblas +openmp', when='+openmp_blas ~int64_blas')
+
     # Note that this forces us to use OpenBLAS until #1712 is fixed
     depends_on('lapack', when='~openmp_blas')
     depends_on('metis')