title: Android M permission install/update behavior
body: <p>With Android Marshmallow there is a new permission model. Implementing the new model was not a big deal for my affected app permissions. But there were some question around the install and update behavior. I identified some scenarios which are important for me. I know the official documentation (<a href="https://developer.android.com/preview/features/runtime-permissions.html" rel="noreferrer">https://developer.android.com/preview/features/runtime-permissions.html</a>) and some things might be clear, but I wanted to be sure.</p>
  
  <ol>
  <li><p>App with target SDK max. 22 installed on an M device and all permissions granted -> update app with new permission model</p></li>
  <li><p>App with target SDK max. 22 installed on an M device and all permissions denied -> update app with new permission model</p></li>
  <li><p>install app with target SDK 23 on a M device</p></li>
  <li><p>App with target SDK 22 or 23 and all permissions granted -> add new permission of an already granted group permission (read_storage) and new permission of another group (read_contacts)</p></li>
  <li><p>App with target SDK 23 and read_contacts granted -> add another permission from contacts group (write_contacts)</p></li>
  </ol>