title: apktool is not generating apk file
body: <p>I used apktool 2.0.0 rc4 version and unpackaged CP.apk file using the tool, then modified a file and trying to re-package it using " apktool b CP test.apk " command</p>
  
  <p>and output goes as below , however there is no test.apk in working directory.</p>
  
  <pre><code>...\apktool&gt;apktool b CP test.apk
  I: Using Apktool 2.0.0-RC3 on CP
  I: Checking whether sources has changed...
  I: Smaling smali folder into classes.dex...
  I: Checking whether resources has changed...
  I: Copying raw resources...
  I: Building apk file...
  I: Copying unknown files/dir...
  </code></pre>
  
  <p>Am I missing anything ?</p>