title: adding a alarm cancel button in the notification
body: <p>I have been working on setting alarms using AlarmManager.</p>
  <p>Set:</p>
  <pre><code>Intent myIntent = new Intent(getApplicationContext(), SessionReceiver.class);
  PendingIntent pendingIntent = PendingIntent.getBroadcast(
                                  getApplicationContext(), reqCode, myIntent, 
                                  PendingIntent.FLAG_UPDATE_CURRENT);
  
  AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
  
  alarmManager.set(AlarmManager.RTC, now.getTimeInMillis(), pendingIntent);
  </code></pre>
  <p>cancel:</p>
  <pre><code>AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
  Intent myIntent = new Intent(getApplicationContext(), SessionReceiver.class);
  PendingIntent pendingIntent = PendingIntent.getBroadcast(
                                  getApplicationContext(), reqCode, myIntent, 
                                  PendingIntent.FLAG_UPDATE_CURRENT);
  
  alarmManager.cancel(pendingIntent);
  </code></pre>
  <p>in my alarm receiver I want to be able to receive a notification which has a button that allows me to call cancelAlarm(). however I don't see the best approach to this and looking for the best and most reliable way of doing this.</p>
  <p>I get the requestCodes so I am able tell which alarm to cancel</p>