Fix for Store issue 818 - system messages not showing up

Fix for https://github.com/Rise-Vision/store/issues/818
- use "sm.slice(0)" to copy array, otherwise changes in the systemMessages are not detected
- removed duplicate reference to the "../../src/js/svc-system-messages.js"
@settinghead the problem I've noticed is that digest cycle is never triggered when new messages are added to the `systemMessages`