Supported platforms: 
Available since: Gideros 2012.09
Inherits from: EventDispatcher
Description
Facebook SDK plugin is available for only iOS as an external plugin. To use facebook module:
1. Download and install Facebook SDK from https://developers.facebook.com/ios/downloads/
2. Add FacebookSDK.framework to your project.
3. Add the backward compatibility headers as described https://developers.facebook.com/docs/howtos/feed-dialog-using-ios-sdk/#step2
4. Add {Gideros Installation Directory}/All Plugins/Facebook/source/iOS/* files to your Xcode project.
5. If enabled, disable "Application does not run in background" property in .plist file.
The Facebook class is defined in module "facebook". Therefore, you need to call
require("facebook") before using it. Loading the Facebook module
also creates a global variable facebook of type Facebook for direct use.
