Removing dependecy to Qt Gradle Plugin from Examples

1. The release cycle of Qt Gradle Plugin is different than Qt. Releasing examples that are dependent to this tool, is conflicting with having separated release cycles.
2. Qt Gradle Plugin depends on the Qt version at runtime (runtime in the context of the Gradle plugin, means the built-time of the target Android project)
3. Qt Gradle plugin should be provided with paths of user environment (there are workarounds for this problem)

Proposition:

1. Removing QtGP inclusion from Android examples.
2. Adding documentation that helps the user to build and deploy Android examples, with or without Qt Gradle Plugin
3. Alternatively, we can deliver example by other means, like github, where the example uses Qt Gradle Plugin.