Fix shebang lines to use #!/usr/bin/env python instead of hard coding a python version.

example.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # coding=utf8
 
 import sleekxmpp

sleekxmpp/__init__.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2.5
+#!/usr/bin/env python
 
 """
     SleekXMPP: The Sleek XMPP Library

sleekxmpp/componentxmpp.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2.6
+#!/usr/bin/env python
 
 """
     SleekXMPP: The Sleek XMPP Library