Fix missing timeout argument for http.client transport (#175)

diff --git a/google/auth/transport/_http_client.py b/google/auth/transport/_http_client.py
index 3cf5583..4a10096 100644
--- a/google/auth/transport/_http_client.py
+++ b/google/auth/transport/_http_client.py
@@ -94,7 +94,7 @@
                 'http.client transport only supports the http scheme, {}'
                 'was specified'.format(parts.scheme))
 
-        connection = http_client.HTTPConnection(parts.netloc)
+        connection = http_client.HTTPConnection(parts.netloc, timeout=timeout)
 
         try:
             _LOGGER.debug('Making request: %s %s', method, url)
diff --git a/tests/transport/compliance.py b/tests/transport/compliance.py
index 6d2a304..50c6d7c 100644
--- a/tests/transport/compliance.py
+++ b/tests/transport/compliance.py
@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import time
+
 import flask
 import pytest
 from pytest_localserver.http import WSGIServer
@@ -47,6 +49,11 @@
         @app.route('/server_error')
         def server_error():
             return 'Error', http_client.INTERNAL_SERVER_ERROR
+
+        @app.route('/wait')
+        def wait():
+            time.sleep(3)
+            return 'Waited'
         # pylint: enable=unused-variable
 
         server = WSGIServer(application=app.wsgi_app)
@@ -62,7 +69,7 @@
         assert response.headers['x-test-header'] == 'value'
         assert response.data == b'Basic Content'
 
-    def test_request_timeout(self, server):
+    def test_request_with_timeout_success(self, server):
         request = self.make_request()
         response = request(url=server.url + '/basic', method='GET', timeout=2)
 
@@ -70,6 +77,12 @@
         assert response.headers['x-test-header'] == 'value'
         assert response.data == b'Basic Content'
 
+    def test_request_with_timeout_failure(self, server):
+        request = self.make_request()
+
+        with pytest.raises(exceptions.TransportError):
+            request(url=server.url + '/wait', method='GET', timeout=1)
+
     def test_request_headers(self, server):
         request = self.make_request()
         response = request(