Clean imports in code

In some part in the code we import objects. In the Openstack style
guidelines they recommend to import only modules.

http://docs.openstack.org/developer/hacking/#imports

Change-Id: I99ca6cda548073d80a5f8a39188a8783bde5b346

doc/source/redirect.py

@@ -12,8 +12,8 @@ from sphinx.util.console import bold
 
 
 def setup(app):
-    from sphinx.application import Sphinx
-    if not isinstance(app, Sphinx):
+    from sphinx import application
+    if not isinstance(app, application.Sphinx):
         return
     app.connect('build-finished', emit_redirects)