Fix to make extension work with Python 2.6 on RHEL 6.3

Note: the pyxmpp2 is not compatible with Python 2.6. To get is running
with the older Python version do the next change in the file:
/usr/lib/python2.6/site-packages/pyxmpp2-2.0alpha2-py2.6.egg/pyxmpp2/etree.py

	<     elif sys.version_info.major < 3:
	---
	>     elif sys.version_info[0] < 3: