Add endpoint handling to Token/Endpoint auth

This auth plugin was initially created before get_endpoint was
available. Implement the get_endpoint method so that we can use the
plugin with relative URLs.

Closes-Bug: #1323926
Change-Id: Ic868f509e708ad29faf86ec5ceeab2a9c98a24fc

auth/test_token_endpoint.py

@@ -33,3 +33,17 @@ class TokenEndpointTest(utils.TestCase):
 
         self.assertEqual(data.text, 'body')
         self.assertRequestHeaderEqual('X-Auth-Token', self.TEST_TOKEN)
+
+    @httpretty.activate
+    def test_basic_endpoint_case(self):
+        self.stub_url(httpretty.GET, ['p'], body='body')
+        a = token_endpoint.Token(self.TEST_URL, self.TEST_TOKEN)
+        s = session.Session(auth=a)
+
+        data = s.get('/p',
+                     authenticated=True,
+                     endpoint_filter={'service': 'identity'})
+
+        self.assertEqual(self.TEST_URL, a.get_endpoint(s))
+        self.assertEqual('body', data.text)
+        self.assertRequestHeaderEqual('X-Auth-Token', self.TEST_TOKEN)