[origin-dev-ui-160] Add support to clone app on create: 'rhc create-app <clone> --from <existing>'

https://trello.com/c/RtkqtAop/160-a-user-can-upgrade-or-clone-an-application-via-rhc-and-the-snapshot-feature
Changes rhc create-app --from to --from-app
Moved check for options dns and git to previous logic
Creating --from-app will no longer copy aliases, still warns about it
Improved message about scaling when creating --from-app