title: how to save bitmap to android gallery
body: <p>unfortunately the solutions I've found didn't work on android 5.1.1.
  I have a bitmap called source. I need to save it directly to my phone's gallery. My manifest contains  <code>&lt;uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /&gt;</code>
  Can you give me a working method to do this?</p>