Ensure we are using Testflight SDK 1.3.

@shazron @aogilvie

I previously updated src/android/libs/TestFlightLib.jar to version 1.3 instead of the one in the example project (I didn't know it existed). In the plugin config.xml, it is actually copying the jar file in src/android/example/platform/android/libs.

I don't think the jar file should be duplicated in src/libs. If we are to use the example project for development of the plugin, then either we should link to the src/android/libs version in the example project or just remove src/android/libs all together.