Install docutils, imagesize, and jinja2

Sphinx requires these.

setup.py

@@ -38,6 +38,9 @@ REQS_FULL = REQS_BASE + REQS_AWS + REQS_OPENSTACK
 REQS_DEV = ([
     'tox>=2.1.1',
     'moto>=1.1.11',
+    'docutils>=0.14',
+    'imagesize>=0.7.1',
+    'jinja2>=2.9.6',
     'sphinx>=1.3.1',
     'flake8>=3.3.0',
     'flake8-import-order>=0.12'] + REQS_FULL