title: Send android notifications with a link to install an apk from a web page
body: <p>I'm looking at building functionality similar to Amazon's Appstore installation flow (http://www.amazon.com/gp/feature.html?docId=1000626391&amp;ref=mas_gs) to get a user to install an apk without going through Google's App Market.</p>
  
  <p>Basically, I would like to provide a web page form that accepts an email or phone number.  In Amazon's case, when the user enters a phone number, it sends a notification to the phone with an actionable link that can be used to finally install an apk.</p>
  
  <p>To build something similar, what is the best way to actually implement this so that the user receives an Android notification that is non-intrusive, but noticeable enough that they can expand it to complete the install process?</p>
  
  <p>Note that at this point, the user does not yet have any version of the target app installed yet, so it's solely reliant on the user providing a phone number to reach them.</p>