YAML config files for compilers and mirrors

.gitignore

lib/spack/spack/cmd/compiler.py

lib/spack/spack/cmd/config.py

lib/spack/spack/cmd/mirror.py

lib/spack/spack/compilers/__init__.py

lib/spack/spack/config.py

lib/spack/spack/stage.py

lib/spack/spack/test/config.py

lib/spack/spack/test/mock_packages_test.py

var/spack/mock_configs/site_spackconfig

var/spack/mock_configs/site_spackconfig/compilers.yaml

var/spack/mock_configs/user_spackconfig