Refactor the flow to use an install activity and a run activity.
Merge branch 'master' of github.com:jhugman/synth-apks
Work in Progress. Succeeding in installing the web app, and being returned  back to Android, however, cannot craft an intent and intent filter to launch the app.

The current intent-filter in fennec doesn't actually do anything, given that the GeckoAppShell.getWebAppIntent() names the class and component to launch, i.e. by-passing the intent-filter all together.

The intention was to have a Launcher catch the Launch intent (when the user launches the app), check if we've installed the app, and if so, call out to WebAppInstaller in Fennec. This would then return a result back to LauncherActivity.onActivityResult(). However, android:noHistory prevents the result ever being returned, so we need to implement a new scheme, e.g.
SynthAPK.LauncherActivity -(launches)-> SynthAPK.InstallerActivity -(launches)-> Fennec.WebappInstaller -(returns to)-> SynthAPK.InstallerActivity -(launches)-> SynthAPK.LauncherActivity -(launches)-> Fennec.Webapp$1.

Where LauncherActivity has android:noHistory, but InstallerActivity has history.
start app via generic WEBAPP action