title: peewee: using Model.get with a default value instead of throwing an exception
body: <p>I just started working with the peewee ORM framework and encountered some kind of behaviour which seems a little strange to me:</p>
  
  <p>Do I really have to use <code>Model.get</code> inside a try/except-clause to get a default value for my query?</p>
  
  <pre><code>user = None
  try:
    user = User.get(User.phone_number == phone_number)
  except User.DoesNotExist:
    pass
  
  if user:
    print u'Hello, {}!'.format(user.first_name)
  else:
    print u'Who are you?'
  </code></pre>
  
  <p>Is there a shortcut for the first five lines of code?</p>