add repr for x509.NameAttribute
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index e280980..7106258 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -75,6 +75,12 @@
     def __ne__(self, other):
         return not self == other
 
+    def __repr__(self):
+        return "<NameAttribute(oid={oid}, value={value!r})>".format(
+            oid=self.oid,
+            value=self.value
+        )
+
 
 class ObjectIdentifier(object):
     def __init__(self, dotted_string):
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 3823120..0927520 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -277,6 +277,13 @@
             x509.ObjectIdentifier('oid'), 'value'
         ) != object()
 
+    def test_repr(self):
+        na = x509.NameAttribute(x509.ObjectIdentifier('2.5.4.3'), 'value')
+        assert repr(na) == (
+            "<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.3, name=commonName"
+            ")>, value='value')>"
+        )
+
 
 class TestObjectIdentifier(object):
     def test_eq(self):