title: android studio won't compile retrofit
body: <p>I generated signed apk of an app I'm working on few dys ago (bea version).
  I'm now trying to compile retrofit to the project, sync stage working good but when I try to run the app I'm getting this error:</p>
  
  <pre><code>Error:Execution failed for task ':app:transformClassesWithDexForDebug'.
  &gt; com.android.build.api.transform.TransformException:
  com.android.ide.common.process.ProcessException:
  org.gradle.process.internal.ExecException: Process 
  'command'/Library/Java/JavaVirtualMachines/jdk1.8.0_51.jdk/Contents/Home/bin/java'' 
  finished with non-zero exit value 2
  </code></pre>
  
  <p>I tried to compile Retrofit on new project and it did compile.</p>
  
  <p>Here are the dependencies (I tried to comment the simple xml alone, didnt help either):</p>
  
  <pre><code>dependencies {
      compile fileTree(include: ['*.jar'], dir: 'libs')
      testCompile 'junit:junit:4.12'
      compile files('libs/UniversalImageLoader195.jar')
      compile 'com.android.support:appcompat-v7:23.1.1'
      compile 'com.android.support:design:23.1.1'
      compile 'com.google.android.gms:play-services:8.4.0'
      compile 'com.loopj.android:android-async-http:1.4.9'
      compile 'com.google.android.gms:play-services-ads:8.4.0'
      compile 'com.google.android.gms:play-services-identity:8.4.0'
      compile 'com.google.android.gms:play-services-gcm:8.4.0'
      //compile 'com.squareup.retrofit2:retrofit:2.0.1'
      //compile 'com.squareup.retrofit2:converter-simplexml:2.0.0-beta3'
  }
  </code></pre>
  
  <p>Any idea?</p>