title: Duplicate files while including butterknife with gradle
body: <p>I have a basic Android app that I created with Android Studio, and I'm having problems adding butterknife to my build.  I get this error:</p>
  
  <pre><code>Error:: duplicate files during packaging of APK C:\apps\orion\app\build\apk\app-debug-unaligned.apk
  Error:Execution failed for task ':app:packageDebug'.
  &gt; Duplicate files copied in APK META-INF/services/javax.annotation.processing.Processor
      File 1: C:\Users\andres\.gradle\caches\modules-2\files-2.1\com.jakewharton\butterknife\4.0.1\f43b36925363701633d01adb8e54df7150397a78\butterknife-4.0.1.jar
      File 2: C:\Users\andres\.gradle\caches\modules-2\files-2.1\com.jakewharton\butterknife\4.0.1\f43b36925363701633d01adb8e54df7150397a78\butterknife-4.0.1.jar
  </code></pre>
  
  <p>My dependencies look like this:</p>
  
  <pre><code>dependencies {
  
      compile 'com.android.support:support-v4:+'
      compile 'com.squareup.dagger:dagger-compiler:1.2.1'
      compile 'com.squareup.dagger:dagger:1.2.1'
      compile 'com.jakewharton:butterknife:4.0.1'
      compile 'com.google.android.gms:play-services:4.0.30'
      compile 'com.android.support:appcompat-v7:+'
      compile project(':lib')
      compile fileTree(dir: 'libs', include: ['*.jar'])
  }
  </code></pre>