title: Card.io on Android doesn't show scan option in release mode
body: <p>We're developing an Android app with Card.IO integrated in it.
  It works fine in the debug mode and shows scan option, however when we make a release build, the scan option disappears and instead the user can only enter the card number manually and it's not what we need.</p>
  
  <p>When we make the release build, we specify in the Android manifest file:</p>
  
  <pre><code>&lt;application android:debuggable="false" ...  
  </code></pre>
  
  <p>And as written in <a href="https://github.com/card-io/card.io-Android-SDK" rel="nofollow">docs</a> we add the following to the proguard file:</p>
  
  <pre><code>-keep class io.card.**
  -keepclassmembers class io.card.** {
      *;
  }
  </code></pre>