Fix pyflakes

Author: pitbulk

src/onelogin/saml2/compat.py

@@ -9,6 +9,16 @@
 
 from __future__ import absolute_import, print_function, with_statement
 
+try:
+    basestring
+except NameError:
+    basestring = str
+
+try:
+    unicode
+except NameError:
+    unicode = str
+
 
 if isinstance(b'', type('')):  # py 2.x
     text_types = (basestring,)  # noqa