Changes to the sample app for callback testing.
Android SDK Updated to 4.0.2
Android samples synchronized with current SDK sample application
Fixed a couple of warnings in the sample app build
Merge branch 'master' of github-wikitude:bigmouth/Wikitude.Xamarin into bigmouth-master

Signed-off-by: Andreas Schacherbauer <andreas.schacherbauer@wikitude.com>

Conflicts:
	.gitignore
	source/samples/Android/WikitudeSampleAndroid/SamplePoidataFromNativeAndUrlListenerScreenshotActivity.cs
Merge branch 'bigmouth-master'

Manual merge
Merge pull request #3 from AndreasSchacherbauerWikitude/master

merges pull request from @bigmouth;