Update the android viewer app and add firefox os app

The new app uses cordova via npm and has a much simpler ui.
The firefox os version still has a bug, which i'm currently fixing, but I pushed this PR for review already since the bug is a regression. Fixing it will not cause a large code change.
The java code is nearly identical to the code in programs/android. The latter will be removed in a new pr when this pr lands.
For the lazy developer (like me) it would be more convenient to get the final product dumped in the toplevel dir of the build, ideally with some version number postfixed to the base name, like it is done for the firefox add-on. So please please us lazy devs :) Same with the APK created.