Catch ServerNotFoundError to retry the request (#532)

diff --git a/googleapiclient/http.py b/googleapiclient/http.py
index a7f14b7..cc622a2 100644
--- a/googleapiclient/http.py
+++ b/googleapiclient/http.py
@@ -173,6 +173,8 @@
         'WSAETIMEDOUT', 'ETIMEDOUT', 'EPIPE', 'ECONNABORTED'}:
         raise
       exception = socket_error
+    except httplib2.ServerNotFoundError as server_not_found_error:
+      exception = server_not_found_error
 
     if exception:
       if retry_num == num_retries: