WIP for Matt's branch

bin/spack

lib/spack/spack/directives.py

lib/spack/spack/package.py

lib/spack/spack/packages.py

lib/spack/spack/patch.py

lib/spack/spack/spec.py

lib/spack/spack/test/mock_packages_test.py

lib/spack/spack/test/package_sanity.py

lib/spack/spack/test/spec_dag.py