re-merging develop

.coveragerc

.flake8

.gitignore

.travis.yml

README.md

bin/spack

etc/spack/modules.yaml

lib/spack/docs/basic_usage.rst

lib/spack/docs/packaging_guide.rst

lib/spack/env/cc

lib/spack/spack/architecture.py

lib/spack/spack/build_environment.py

lib/spack/spack/cmd/compiler.py

lib/spack/spack/cmd/create.py

lib/spack/spack/cmd/module.py

lib/spack/spack/compiler.py

lib/spack/spack/compilers/clang.py

lib/spack/spack/compilers/gcc.py

lib/spack/spack/compilers/intel.py

lib/spack/spack/compilers/nag.py