close the Dashboard when the user disables/updates the addon
suppress duplicate error notification when adding app
Merge pull request #417 from mykmelez/close-helper-tab

close Dashboard when user disables/updates addon (fixes #416)
Merge pull request #418 from mykmelez/duplicate-message
set ADB state before notifying observers of a change to it
Merge pull request #419 from mykmelez/adb-ready

set ADB state before notifying observers of a change to it