Use correct language for Bash and Python snippets.

Change-Id: If417af59574802c75b4721559c05bc5a2271df61
Updates to 'Command Reference' appendix

Included updates to the Command Reference appendix. New commands
and some consistency changes made to neutron, nova, keystone, heat,
swift and cinder sections.

Change-Id: I5bbd03062ca4205f4d7c1e75913bec292d6ac7fa
Merge "Use correct language for Bash and Python snippets."
Merge "Updates to 'Command Reference' appendix"