PWASupported

[jameslockman]

1. Progressive Web Apps are great, unless you have clients with older browsers that don't support them. It has been possible for a long time to save a web site to the home screen on iOS and Android, but these copies don't update unless you delete the home screen icon. We are hoping to provide guidance to users that their browser doesn't support PWA, and that they may need to refresh their local copy of the site.
2. Please add a test that returns true if the browser configuration supports PWA.