rename old scripts for better urls
add /s/xxx/stage/y/puzzle/z urls
stage routing and redirecting to canonical paths
Merge branch 'finished' into nice-script-urls
Merge branch 'finished' into nice-script-urls
refactor ScriptLevelsController#show so it's clearer why and when we are redirecting
fix order of script.stages and script.script_levels
Merge branch 'finished' into nice-script-urls
use cycle rails helper
Merge pull request #613 from code-dot-org/nice-script-urls

new script and level urls
undo unintended dependent: destroy
Merge pull request #638 from code-dot-org/finished

dtt