Fix X509ExtTests to actually do proper leak checking and fix some more leaks
diff --git a/OpenSSL/test/test_crypto.py b/OpenSSL/test/test_crypto.py
index 1393876..a75fcff 100644
--- a/OpenSSL/test/test_crypto.py
+++ b/OpenSSL/test/test_crypto.py
@@ -276,6 +276,7 @@
         Create a new private key and start a certificate request (for a test
         method to finish in one way or another).
         """
+        super(X509ExtTests, self).setUp()
         # Basic setup stuff to generate a certificate
         self.pkey = PKey()
         self.pkey.generate_key(TYPE_RSA, 384)
@@ -294,6 +295,15 @@
         self.x509.set_notAfter(expire)
 
 
+    def tearDown(self):
+        """
+        Forget all of the pyOpenSSL objects so they can be garbage collected,
+        their memory released, and not interfere with the leak detection code.
+        """
+        self.pkey = self.req = self.x509 = self.subject = None
+        super(X509ExtTests, self).tearDown()
+
+
     def test_str(self):
         """
         The string representation of :py:class:`X509Extension` instances as returned by