Merge branch 'custom_modulefiles_from_config' of https://github.com/epfl-scitas/spack into epfl-scitas-custom_modulefiles_from_config

Improve error message for wrong config section names

Conflicts:
	lib/spack/spack/config.py

This reverts commit 71e49e28.

QA : make qa checking less painful

- was missing the obvious.

- user can run the same script.

- Exempt overlong URL lines from checks.
- Omit some of the more painful PEP items.

Add a few more python packages

astyle: compile with spack_cxx

openmpi : added variants

- Consider removing this once names like `cmake` and `configure` are
  moved to a sensible namespace.