[bug 1015788] Add flake8 linting

* adds flake8_lint.sh script
* fixes all flake8 issues in existing python files
* adds flake8_lint.pre-commit script which creates the git pre-commit
  hook
Merge pull request #339 from willkg/flake8

[bug 1015788] Add flake8 linting
Update coding conventions

This adds notes about the linting scripts. Plus it removes a bunch of
stuff.