Tutorial fixes.
Merge pull request #565 from arjclark/tutorial-fixes

rose documentation: corrections to rose-rug-suites slides
rose install - improve example site config
rose installation: update following feedback
rose suite-clean: new command.
rose suite-clean: more documentation.
rose suite-clean: fix checking for running suite.
rose edit: fix new file checkbox state
Merge pull request #568 from benfitzpatrick/rose-edit-fix-file-sections-page

rose edit: fix new file checkbox state
Merge pull request #566 from benfitzpatrick/rose-install-improve-example-conf

rose installation - improve example site config
Merge branch 'master' into 548.rose-suite-clean
Merge pull request #567 from matthewrmshin/548.rose-suite-clean

rose suite-clean: new command
Closes #548