Remove #noqa from most common imports and add them to import_exceptions

We have a lot of import with #noqa that is there to ignore h302,
because it's traditional to import and use a name directly, instead
of a whole module. This hides other errors and gives people the
impression that it's actually fine to import non-modules, you just
have to slap #noqa on those lines.

I went through the code and identified about a dozen names that are
most commonly imported this way. I remove the #noqa tag from them,
and added them to the list in import_exceptions.

I also removed a few unused imports that were revealed in the process.

Change-Id: I27afb8e2b1d4759ec974ded9464d8f010312ee78

1 files changed, 21 insertions, 1 deletions

diff --git a/HACKING.rst b/HACKING.rst
index 8d394d651..b413c8a23 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -3,7 +3,27 @@ Horizon Style Commandments
 
 - Step 1: Read the OpenStack Style Commandments
   http://docs.openstack.org/developer/hacking/
-- Step 2: Read on
+- Step 2: The following names can be imported directly, without triggering the
+  "H302: import only modules" flake8 warning::
+
+    collections.defaultdict,
+    django.conf.settings,
+    django.core.urlresolvers.reverse,
+    django.core.urlresolvers.reverse_lazy,
+    django.template.loader.render_to_string,
+    django.utils.datastructures.SortedDict,
+    django.utils.encoding.force_unicode,
+    django.utils.html.conditional_escape,
+    django.utils.html.escape,
+    django.utils.http.urlencode,
+    django.utils.safestring.mark_safe,
+    django.utils.translation.pgettext_lazy,
+    django.utils.translation.ugettext_lazy,
+    django.utils.translation.ungettext_lazy,
+    operator.attrgetter,
+    StringIO.StringIO
+
+- Step 3: Read on
 
 Horizon Specific Commandments
 -----------------------------