call simulator.sendListApps on add/undo error to prevent silent errors
update dashboard app list before start validation and refresh again before error/success handling
update cached manifest before validate app and added RUNNING and WARNINGS validation result
tweaks on comment to better explain reasons to call Simulator.sendListApps multiple times
Merge pull request #375 from rpl/fix-addapp-silent-error

FIX: prevent silent errors on add/undo error