Merge pull request #124 from scheibelp/features/testinstall-cmd

lib/spack/spack/build_environment.py

lib/spack/spack/cmd/test-install.py

lib/spack/spack/package.py

lib/spack/spack/stage.py

lib/spack/spack/test/__init__.py

lib/spack/spack/test/unit_install.py