Add management command utility function to deployment.

Calling python for manage.py was inconsistent.
Merge branch 'bug-906882-xml-sitemap-full' of https://github.com/kyoshino/bedrock into bug-906882-xml-sitemap-full
Merge branch 'management-cmd-utility-function-deployment' of https://github.com/pmclanahan/bedrock into bug-906882-xml-sitemap-full