Add more quality checks to tox config.

- pylint and flake8 for general purpose
- mccabe for function complexity
- pyroma for packaging/distribution
- pep257 for docstring quality

Author: dnozay

tox.ini

@@ -1,8 +1,8 @@
 [tox]
-envlist = begin,py{26,27,33,34},py27-django{lts,prev,curr},end
+envlist = begin,py{26,27,33,34},py27-django{lts,prev,curr},end,quality
 
 [testenv]
-deps=
+deps =
     coverage
     djangolts: django==1.4.22
     djangoprev: django==1.6.11
@@ -18,3 +18,17 @@ commands = coverage erase
 commands =
     coverage report --omit='.tox/*'
     coverage html --omit='.tox/*'
+
+[testenv:quality]
+ignore_outcome = True
+deps =
+    mccabe
+    pylint
+    flake8
+    pyroma
+    pep257
+commands =
+    pylint xmlrunner tests
+    flake8 --max-complexity 10
+    pyroma .
+    pep257