Added swift3.Request

This patch introduces S3 request object, swift3.Request, and moves request
manipulation code like header validation or translation into request.py.

The main purpose of this change is to improve code maintainability.  After this
patch, Swift requests and responses are completely distinguished from S3's
ones, and middleware.py no longer touch swob.Request and swob.Response.  All
the controllers in middleware.py can focus on how requests flow into Swift.

Change-Id: I7545f1ebcb5f36a7cb78b812ac6f0124beee5cb8

swift3/exception.py

@@ -0,0 +1,22 @@
+# Copyright (c) 2014 OpenStack Foundation.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+class S3Exception(Exception):
+    pass
+
+
+class NotS3Request(S3Exception):
+    pass