Added a tox configuration to verify said sdist is complete.

tox.ini

@@ -9,3 +9,17 @@ commands =
     python -m unittest discover
 deps =
     -rdev_requirements.txt
+
+[testenv:check]
+basepython = python3.4
+deps =
+    docutils
+    check-manifest
+    flake8
+    collective.checkdocs
+    pygments
+usedevelop = true
+commands =
+    python setup.py checkdocs
+    python setup.py check --strict --metadata
+    check-manifest {toxinidir}