Use same dependencies for tox -e docs and readthedocs

Author: Jon Wayne Parrott

tox.ini

@@ -65,7 +65,6 @@ commands =
 [testenv:docs]
 basepython = python3.5
 deps =
-  {[testenv]deps}
   sphinx
   -r{toxinidir}/docs/requirements-docs.txt
 commands = make -C docs html