title: Convert UTC datetime string to local datetime
body: <p>I've never had to convert time to and from UTC. Recently had a request to have my app be timezone aware, and I've been running myself in circles. Lots of information on converting local time to UTC, which I found fairly elementary (maybe I'm doing that wrong as well), but I can not find any information on easily converting the UTC time to the end-users timezone.</p>
  
  <p>In a nutshell, and android app sends me (appengine app) data and within that data is a timestamp. To store that timestamp to utc time I am using:</p>
  
  <pre><code>datetime.utcfromtimestamp(timestamp)
  </code></pre>
  
  <p>That seems to be working. When my app stores the data, it is being store as 5 hours ahead (I am EST -5)</p>
  
  <p>The data is being stored on appengine's BigTable, and when retrieved it comes out as a string like so: </p>
  
  <pre><code>"2011-01-21 02:37:21"
  </code></pre>
  
  <p>How do I convert this string to a DateTime in the users correct time zone?</p>
  
  <p>Also, what is the recommended storage for a users timezone information?  (How do you typically store tz info ie: "-5:00" or "EST" etc etc ?) I'm sure the answer to my first question might contain a parameter the answers the second.  </p>