title: buildozer/Kivy NONETYPE splitlines error
body: <p>When I try to compile my APK in the VM version of Buildozer I am getting this error. </p>
  
  <pre><code>Traceback (most recent call last):
  File "/usr/local/bin/buildozer", line 11, in &lt;module&gt;
  load_entry_point('buildozer==0.33', 'console_scripts', 'buildozer')()
  File "/usr/local/lib/python2.7/dist-packages/buildozer/scripts/client.py",         line 13, in main
  Buildozer().run_command(sys.argv[1:])
    File "/usr/local/lib/python2.7/dist-packages/buildozer/__init__.py", line 1058, in run_command
  self.target.run_commands(args)
  File "/usr/local/lib/python2.7/dist-packages/buildozer/target.py", line 91, in run_commands
  func(args)
  File "/usr/local/lib/python2.7/dist-packages/buildozer/target.py", line 101, in cmd_debug
  self.buildozer.prepare_for_build()
  File "/usr/local/lib/python2.7/dist-packages/buildozer/__init__.py", line 176, in prepare_for_build
  self.target.install_platform()
  File "/usr/local/lib/python2.7/dist-packages/buildozer/targets/android.py", line 470, in install_platform
  self._install_android_packages()
  File "/usr/local/lib/python2.7/dist-packages/buildozer/targets/android.py", line 407, in _install_android_packages
  packages = self._android_list_sdk()
  File "/usr/local/lib/python2.7/dist-packages/buildozer/targets/android.py", line 336, in _android_list_sdk
  for x in available_packages.splitlines()
  AttributeError: 'NoneType' object has no attribute 'splitlines'
  </code></pre>
  
  <p>I have not found an answer anywhere that relates to this issue. Thanks for your help. </p>