title: I want to save and load the Area description in Google Tango kit
body: <p>So I build Assets/TangoSDK/Examples/Scenes/AreaLearning. But, when the _PopulateList function calls, the error is caused.
  <strong>E/tango: file_io.cc:539 Error(13) opening path: /data/data/com.google.tango/files/Tango/ADFs/ failed with error Permission denied.</strong></p>
  
  <p>And when the saveCurrent() functions calls, the error is caused. 
  <strong>E/tango: file_io.cc:773 Couldn't prepare directory /data/data/com.google.tango/files/Tango/ADFs/ - -1</strong></p>
  
  <p>I think this app has not permission at /data/data/com.google.tango/*.</p>
  
  <p>How do I solve this problem?</p>