title: Change every occurrence of a date to another format with regex
body: <p>I'm doing my first steps with regex and I'm still a little bit confused about the syntax. I want to detect the end of sentences trough a period. I already wrote most of the rules to make this work but I still have problems with dates. 
  This is my expression to change every period to a backlash in a date:</p>
  
  <pre><code>re.sub('\d+\.(\s)?\w+(\.)?(\s)?\d+', '\d+/\w+/\d+', text)
  </code></pre>
  
  <p>This is supposed to work with 14.8.2012 but also 14. August 2012. It seems like it recognizes the dates but it won't change them to the new format. What am I doing wrong?</p>
  
  <p>Cheers,
  Marcel   </p>