Keeping icons in disabled state when SD-card is unmounted

> changing shortcutInfo.isDisabled to be a flag based variable
> on received OnPackageUnavailable, icons are disabled from desktop
instead of being removed. Icons in all apps are removed

Bug: 15852084
Bug: 16238283
Change-Id: I126d23c709682a917d4bbb84de71032593dce8f9