title: When using beeware build android It gives "can't open file 'setup.py': [Errno 2] No such file or directory"
body: <p>When using beeware build android  It gives "can't open file 'setup.py': [Errno 2] No such file or directory"
  I really do not know what wrong I am doing here. Below is the standard code from beeware sample app.  When I run this app it runs properly in the windows environment but when I try to deploy on android through the beeware command i.e. "<strong>beeware build android</strong>" I get the error "<strong>can't open file 'setup.py': [Errno 2] No such file or directory</strong>". Any ideas any one for me to try.</p>
  
  <pre><code>import toga
  
  
  def button_handler(widget):
      print("hello")
  
  
  def build(app):
      box = toga.Box()
  
  button = toga.Button('Hello world', on_press=button_handler)
  button.style.padding = 50
  button.style.flex = 1
  box.add(button)
  
  return box
  
  
  def main():
      return toga.App('First App', 'org.beeware.helloworld', startup=build)
  
  
  if __name__ == '__main__':
      main().main_loop()
  </code></pre>