title: Python 2.7: type object "ElementTree" has no attribute "register_namespace"
body: <p>with this python 2.7.3 (or 2.7.0) code I want to change the value of the attribute "android:versionCode='2'", which has the namespace prefix "android":</p>
  
  <pre class="lang-py prettyprint-override"><code>#!/usr/bin/python
  from xml.etree.ElementTree import ElementTree, dump
  import sys, os
  
  # Problem here:
  ElementTree.register_namespace("android", "http://schemas.android.com/apk/res/android")
  
  tree = ElementTree()
  tree.parse("AndroidManifest.xml")
  root = tree.getroot()
  root.attrib["{http://schemas.android.com/apk/res/android}versionCode"] = "3"
  
  dump(tree)
  </code></pre>
  
  <p>When not using the line of code commented with "Problem here", ElementTree is auto-naming the namespace alias for <a href="http://schemas.android.com/apk/res/android">http://schemas.android.com/apk/res/android</a> to "ns0" (resulting in "ns0:versionCode='3'".</p>
  
  <p>Thus I'm using ElementTree.register_namespace to map the namespace url to the alias name "android", which is documented <a href="http://docs.python.org/library/xml.etree.elementtree.html#xml.etree.ElementTree.register_namespace">here</a>.</p>
  
  <p>The error I get when I try to do this is:</p>
  
  <pre><code>AttributeError: type object 'ElementTree' has no attribute 'register_namespace'
  </code></pre>
  
  <p>Anybody knows why this is not working? This method should be available in python 2.7.</p>