title: cannot find zipalign.exe from android sdk
body: <p>what do I need to download to get the zip-align tool to use on my apk file?
  I am using the ionic3 guide for developing for Android. when I type this:</p>
  
  <pre><code>zip-align -v 4 android-release-unsigned. apk HelloWorld.apk
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>'zip-align' is not recognized as an internal or external command,
  operable program or batch file.
  </code></pre>
  
  <p>I want to build for google playstore</p>