fixes #416
	renamed:    docs/gettingstarted/tutorial/cleanup.rst -> docs/advanced/cleanup.rst
	modified:   docs/advanced/index.rst
	modified:   docs/gettingstarted/tutorial/index.rst
	modified:   docs/advanced/cleanup.rst
	modified:   docs/advanced/cleanup.rst
	modified:   docs/gettingstarted/tutorial/vagrant-setup.rst
	modified:   docs/advanced/cleanup.rst
	modified:   docs/advanced/cleanup.rst
addresses final review comments
spelling fix
Merge pull request #674 from ClusterHQ/document-purge-state-416

Document how to purge state created by Flocker