Refactored Watcher codebase to add py34 support

Even though Watcher was mentioning python 3.4 as supported, it
really wasn't the case as all the unit tests were not passing in this
version of Python.

This patchset fixes all the failing tests in Python 3.4 while
keeping Watcher Python 2.7 compatible.

DocImpact
BugImpact
Change-Id: Ie74acc08ef0a2899349a4b419728c89e416a18cb

watcher/api/middleware/parsable_error.py

@@ -13,7 +13,6 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.
-
 """
 Middleware to replace the plain text message body of an error
 response with one formatted so the client can parse it.
@@ -24,9 +23,9 @@ Based on pecan.middleware.errordocument
 import json
 from xml import etree as et
 
-import webob
-
 from oslo_log import log
+import six
+import webob
 
 from watcher.common.i18n import _
 from watcher.common.i18n import _LE
@@ -69,8 +68,9 @@ class ParsableErrorMiddleware(object):
         app_iter = self.app(environ, replacement_start_response)
         if (state['status_code'] // 100) not in (2, 3):
             req = webob.Request(environ)
-            if (req.accept.best_match(['application/json', 'application/xml'])
-                    == 'application/xml'):
+            if (req.accept.best_match(['application/json', 'application/xml']
+                                      ) == 'application/xml'
+                ):
                 try:
                     # simple check xml is valid
                     body = [et.ElementTree.tostring(
@@ -83,9 +83,13 @@ class ParsableErrorMiddleware(object):
                             + '</error_message>']
                 state['headers'].append(('Content-Type', 'application/xml'))
             else:
+                if six.PY3:
+                    app_iter = [i.decode('utf-8') for i in app_iter]
                 body = [json.dumps({'error_message': '\n'.join(app_iter)})]
+                if six.PY3:
+                    body = [item.encode('utf-8') for item in body]
                 state['headers'].append(('Content-Type', 'application/json'))
-            state['headers'].append(('Content-Length', len(body[0])))
+            state['headers'].append(('Content-Length', str(len(body[0]))))
         else:
             body = app_iter
         return body