Could not create plugin of type 'AppPlugin'
Ok, is really annoying. This is because we are not using the "proper" version of Gradle with Android. Even up to this date Gradle is already to the version 2.2 and Google still hasn't fixed it. Well, it seems that the Gradle version that works with Android tools are 1.10, 1.11 and 1.12. In my case I use the version 1.12.
Let's assure that we have enabled the Android Support Repository. So from Android Studio, Eclipse or another mean initialize the SDK Manager and look for Extras | Android Support Repository and install it if not is installed.
Use your favourite text editor (mousepad, pluma, etc) and open ~/.bashrc and add these lines
export ANDROID_HOME=<path where the Android SDK is>
export GRADLE_HOME=<path where our Gradle version is>
With ANDROID_HOME we avoid another Gradle error of the type
Ambiguous method overloading for method java.io.FileOk, save and reopen our bash terminal to work with gradle scripts. It should works fine from now.