Modernize use of range()

In Python 3, range() behaves like the old xrange().
The difference between range() and xrange() is usually not significant,
especially if the whole result is iterated over.

Convert xrange() usage to range() for small ranges.
Use modern idioms in a few other uses of range().

Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipatests/test_xmlrpc/test_vault_plugin.py

@@ -34,7 +34,7 @@ symmetric_vault_name = u'symmetric_test_vault'
 asymmetric_vault_name = u'asymmetric_test_vault'
 
 # binary data from \x00 to \xff
-secret = ''.join(chr(c) for c in xrange(0, 256))
+secret = ''.join(chr(c) for c in range(0, 256))
 
 password = u'password'
 other_password = u'other_password'