NEW: Support for specifying the SSL protocol version (Python v2) (#9)

* Support for specifying the SSL protocol version (Python v2)

This fixes #329.
diff --git a/python2/ssl_protocol_test.py b/python2/ssl_protocol_test.py
new file mode 100755
index 0000000..bac84c0
--- /dev/null
+++ b/python2/ssl_protocol_test.py
@@ -0,0 +1,57 @@
+"""Tests for SSL handling in httplib2."""
+
+import httplib2
+import os
+import ssl
+import sys
+import unittest
+
+
+class TestSslProtocol(unittest.TestCase):
+
+  def testSslCertValidationWithInvalidCaCert(self):
+    if sys.version_info >= (2, 6):
+      http = httplib2.Http(ca_certs='/nosuchfile')
+      if sys.version_info >= (2, 7):
+        with self.assertRaises(IOError):
+          http.request('https://www.google.com/', 'GET')
+      else:
+        self.assertRaises(
+            ssl.SSLError, http.request, 'https://www.google.com/', 'GET')
+
+  def testSslCertValidationWithSelfSignedCaCert(self):
+    if sys.version_info >= (2, 7):
+      other_ca_certs = os.path.join(
+          os.path.dirname(os.path.abspath(httplib2.__file__ )), 'test',
+          'other_cacerts.txt')
+      http = httplib2.Http(ca_certs=other_ca_certs)
+      if sys.platform != 'darwin':
+        with self.assertRaises(httplib2.SSLHandshakeError):
+          http.request('https://www.google.com/', 'GET')
+
+  def testSslProtocolTlsV1AndShouldPass(self):
+    http = httplib2.Http(ssl_version=ssl.PROTOCOL_TLSv1)
+    urls = ['https://www.amazon.com',
+            'https://www.apple.com',
+            'https://www.twitter.com']
+    for url in urls:
+      if sys.version_info >= (2, 7):
+        self.assertIsNotNone(http.request(uri=url))
+
+  def testSslProtocolV3AndShouldFailDueToPoodle(self):
+    http = httplib2.Http(ssl_version=ssl.PROTOCOL_SSLv3)
+    urls = ['https://www.amazon.com',
+            'https://www.apple.com',
+            'https://www.twitter.com']
+    for url in urls:
+      if sys.version_info >= (2, 7):
+        with self.assertRaises(httplib2.SSLHandshakeError):
+          http.request(url)
+        try:
+          http.request(url)
+        except httplib2.SSLHandshakeError as e:
+          self.assertTrue('sslv3 alert handshake failure' in str(e))
+
+
+if __name__ == '__main__':
+  unittest.main()