title: Empty notification with phonegap-plugin-push
body: <p>I'm using push notifications in my ionic+phonegap-plugin-push app without problem.</p>
  
  <p>Everything works fine BUT, once a day or so I get a blank notification, no message, nothing but the app icon and there is no way you can remove that notification from the "notification center".</p>
  
  <p><img src="https://i.stack.imgur.com/nMGv3.png" width="300"></p>
  
  <p>It seems to happen only in android so I guess is related to the push plugin or maybe something related to the new firebase back, ionic, ...no idea seriously.</p>
  
  <p>Any ideas? According to the logs in the server the payloads are the right ones and I'm not able to reproduce it.</p>
  
  <p>I'm using:</p>
  
  <ul>
  <li>cordova --version: 6.4.0</li>
  <li>cordova platform version android: 5.1.1</li>
  <li>cordova plugin version: 
  
  <ul>
  <li>cordova-plugin-app-event 1.2.0 "Application Events"</li>
  <li>cordova-plugin-background-fetch 4.0.0 "CDVBackgroundFetch"</li>
  <li><strong>cordova-plugin-background-mode 0.7.1 "BackgroundMode"</strong></li>
  <li>cordova-plugin-badge 0.7.4 "Badges"</li>
  <li>cordova-plugin-camera 2.3.1 "Camera"</li>
  <li>cordova-plugin-compat 1.1.0 "Compat"</li>
  <li>cordova-plugin-console 1.0.5 "Console"</li>
  <li>cordova-plugin-datepicker 0.9.2 "DatePicker"</li>
  <li>cordova-plugin-device 1.1.4 "Device"</li>
  <li>cordova-plugin-file 4.3.1 "File"</li>
  <li>cordova-plugin-file-transfer 1.6.1 "File Transfer"</li>
  <li>cordova-plugin-inappbrowser 1.6.1 "InAppBrowser"</li>
  <li>cordova-plugin-network-information 1.3.1 "Network Information"</li>
  <li>cordova-plugin-splashscreen 4.0.1 "Splashscreen"</li>
  <li>cordova-plugin-statusbar 2.2.1 "StatusBar"</li>
  <li>cordova-plugin-vibration 2.1.3 "Vibration"</li>
  <li>cordova-plugin-whitelist 1.3.1 "Whitelist"</li>
  <li>ionic-plugin-deploy 0.6.5 "IonicDeploy"</li>
  <li>ionic-plugin-keyboard 2.2.1 "Keyboard"</li>
  <li><strong>phonegap-plugin-push 1.8.4 "PushPlugin"</strong></li>
  </ul></li>
  </ul>