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.
This file and the icon-128.png do not yet end up in the build (both www and package.zip), instead the manifest is the one of Cordova right now:
```
{
    "launch_path": "/index.html",
    "installs_allowed_from": [
        "*"
    ],
    "version": "0.0.1",
    "name": "WebODF",
    "pkgName": "org.webodf",
    "description": "A sample Apache Cordova application that responds to the deviceready event.",
    "developer": {
        "name": "Apache Cordova Team",
        "url": "http://cordova.io"
    },
    "icons": {}
}
```