title: Android auto update
body: <p>I see a lot of SO questions and answers relating to auto update that amount to the correct answer being "it can't be done without the user's participation". However, many of my apps have the "update automatically" checkbox checked in the Play store and I see them auto-updating and then notifying me in the notification bar that they have, in fact, updated.</p>
  
  <p>So clearly it *can be done... I'd like to know what my various options are for getting my app to have this feature.  Does it need to be in the google Play store? Can it be in some alternate store instead? Is it available to apks that are side loaded... etc.</p>
  
  <p>TIA.</p>