Improve docs build

Starting in Django 1.7, standalone scripts, such as a sphinx build
require that django.setup() be called first. See:
https://docs.djangoproject.com/en/1.8/releases/1.7/#standalone-scripts
It does not always necessary, but it is needed to avoid warnings
when creating autoindex.
Note that horizon no longer generates the autoindex to avoid warnings.

Drops setenv DJANGO_SETTINGS_MODULE in docs env in tox.ini.
DJANGO_SETTINGS_MODULE is configured in doc/source/conf.py,
so there is no need to pass envvar.

Add warning-is-error sphinx setting to avoid doc build warnings.

Change-Id: I2de87c0df05abf589c90fb3ad691322e1125c310

doc/source/conf.py

@@ -28,6 +28,8 @@ import os
 import subprocess
 import sys
 
+import django
+
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 ROOT = os.path.abspath(os.path.join(BASE_DIR, "..", ".."))
 
@@ -37,8 +39,12 @@ sys.path.insert(0, ROOT)
 os.environ.setdefault('DJANGO_SETTINGS_MODULE',
                       'magnum_ui.test.settings')
 
-from magnum_ui \
-    import version as magnumui_ver
+# Starting in Django 1.7, standalone scripts, such as a sphinx build
+# require that django.setup() be called first.
+# https://docs.djangoproject.com/en/1.8/releases/1.7/#standalone-scripts
+django.setup()
+
+from magnum_ui import version as magnumui_ver
 
 
 def write_autodoc_index():
@@ -270,7 +276,7 @@ html_theme_options = {
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+html_static_path = ['']
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.

setup.cfg

@@ -26,3 +26,4 @@ packages =
 all_files = 1
 build-dir = doc/build
 source-dir = doc/source
+warning-is-error = 1

tox.ini

@@ -57,7 +57,6 @@ commands =
   echo "execute `npm run test`"
 
 [testenv:docs]
-setenv = DJANGO_SETTINGS_MODULE=magnum_ui.test.settings
 commands = python setup.py build_sphinx
 
 [testenv:releasenotes]