Notification Icons

- Notification Icons upload/download/copy changed
- included different pngs for hdpi/mdpi/xhdpi and Android v9+11

- standard Icons as discussed with design team
- LintWarning fixed (Usabilty&Icons Icons Expected Size)

here is a link that describes, why we need different folders for different Android versions: http://developer.android.com/guide/practices/ui_guidelines/icon_design_status_bar.html
icons were taken from: http://android-ui-utils.googlecode.com/hg/asset-studio/dist/index.html