- Ported old run-flake8-tests qa script to `spack flake8` command.
- New command does not modify files in the source tree
- Copies files to a temp stage modifies them there, and runs tests.
- Updated docs and `run-flake8-tests` script to call `spack flake8`.
* Warn user if flake8 can't find setuptools
* Add missing dependencies of flake8
* Updates to py-autopep8, make packages activateable
* Check for presence of setuptools for Sphinx too
* Fix bug in order of commands