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.
Please make `WebODF/platforms/firefoxos/build/package.zip` a variable, pointing to a file in the toplevel build dir and postfixed with the version, with the var being set it in the toplevel CMakeLists.txt, like done for the firefox extension product (FIREFOX_EXTENSION_ODFVIEWER). Same with `WebODF-debug.apk`
For the sake of consistency and thus less complexity and easier maintainance for people who did not write this code :)