Gradle version 1.8 is required. Current version is 1.6

I am not sure if this will help you but here is what fixed it for me:

Open up this file in your project:

<Project>/gradle/wrapper/gradle-wrapper.properties

Edit the distributionUrl line and set it too:

distributionUrl=https\://services.gradle.org/distributions/gradle-1.8-all.zip

Rebuild your project.

Update: You might want to use gradle-2.8-all.zip now.