Added tox.ini and test-requirements for testing

Added tox.ini and test-requirements.txt to allow for .rst
document validation, and other tests to check updates and
changes. The goal will be to add a verify and gate process
to the Defcore project repository.

Change-Id: I9fceae7569d7e3df53c3c3d2567a691dbd406a55

test-requirements.txt

@@ -0,0 +1 @@
+doc8

tox.ini

@@ -0,0 +1,14 @@
+[tox]
+minversion = 1.6
+skipsdist = True
+
+[testenv]
+basepython=python2.7
+setenv =
+   VIRTUAL_ENV={envdir}
+deps = -r{toxinidir}/test-requirements.txt
+
+[testenv:doc8]
+commands =
+  doc8 -e .rst 2015.03.rst 2015.04.rst 2015.next.rst CoreDefinition.rst \
+               GovernanceProcess.rst ProcessCycles.rst README.rst lexicon.rst