title: java.lang.noClassDefFoundError on Android 4.4.4, works on 5.0+
body: <p>I am getting this error:</p>
  
  <pre><code>12-17 03:59:18.767 7516-8610/io.ustube.ustube E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
                                                              Process: io.ustube.ustube, PID: 7516
                                                              java.lang.RuntimeException: An error occured while executing doInBackground()
                                                                  at android.os.AsyncTask$3.done(AsyncTask.java:300)
                                                                  at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
                                                                  at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
                                                                  at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                                                                  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
                                                                  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
                                                                  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
                                                                  at java.lang.Thread.run(Thread.java:841)
                                                               Caused by: java.lang.NoClassDefFoundError: com.google.gson.internal.$Gson$Preconditions
                                                                  at com.google.gson.reflect.TypeToken.&lt;init&gt;(TypeToken.java:72)
                                                                  at com.google.gson.reflect.TypeToken.get(TypeToken.java:296)
                                                                  at com.google.gson.Gson.toJson(Gson.java:644)
                                                                  at com.google.gson.Gson.toJson(Gson.java:631)
                                                                  at com.google.gson.Gson.toJson(Gson.java:586)
                                                                  at com.google.gson.Gson.toJson(Gson.java:566)
                                                                  at io.ustube.ustube.LoginActivity$VerifyTask.doInBackground(LoginActivity.java:338)
                                                                  at io.ustube.ustube.LoginActivity$VerifyTask.doInBackground(LoginActivity.java:310)
                                                                  at android.os.AsyncTask$2.call(AsyncTask.java:288)
                                                                  at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                                  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
                                                                  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
                                                                  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
                                                                  at java.lang.Thread.run(Thread.java:841) 
  </code></pre>
  
  <p>but I know that the mentioned class is a dependency. I've looked through the jar file myself. Also, I only get this error below 5.0.</p>
  
  <p>My gradle file includes <code>compile 'com.google.code.gson:gson:2.5'</code></p>