Used short_name for Android launcher_name

Android has a `launcher_name` property that fits perfectly in the definition of the manifest `short_name`: https://developer.chrome.com/apps/manifest/name#short_name




Would be better to change the value in res/values/strings.xml

It's a bit of a nitpick though, so feel free to just add a "TODO: Change this in res/values/strings.xml instead" comment here and I'll merge it in.