Removed dependency on unittest2, also merged requirements.txt for py 2.x and 3.x
diff --git a/tests/test_integers.py b/tests/test_integers.py
index f504e45..118204a 100644
--- a/tests/test_integers.py
+++ b/tests/test_integers.py
@@ -16,11 +16,11 @@
 
 '''Tests integer operations.'''
 
-import unittest2
+import unittest
 
 import rsa.core
 
-class IntegerTest(unittest2.TestCase):
+class IntegerTest(unittest.TestCase):
 
     def setUp(self):
         (self.pub, self.priv) = rsa.newkeys(64)