Fixes to 'schema' shell app after acceptance testing

o If no action arguments are provided then fall back to listing indexes
o Unrecognized options (for all apps) will fail
o Label names in all apps can be prefixed with ':' if desired
o No shell tests output anything to System.out anymore
Merge pull request #735 from tinwelint/2.0-shell-schema-app

Fixes to 'schema' shell app after acceptance testing