Add tests for setup

Test write_git_changelog, generate_authors, get_cmdclass, and
parse_dependency_links. Also test private _run_shell_command
function.

Change-Id: I583d679afc1dc805c920b4beffc2f664833aabd0
Fix PEP8 error in oslo-rootwrap

Fix a PEP8 error uncovered during the cinder import of the rootwrap
module. A bit weird oslo's own tests didn't catch it.

Change-Id: Ib107023dd6e4178dd51b358cf9374e7a8468d1bf
Merge "Add tests for setup"