tox: Update pytest-flakes to 1.0.0.

Upstream changelog:

- Fix issue #6 - support PEP263 for source file encoding.
- Clarified license to be MIT like pytest-pep8 from which this is derived.

tox.ini

@@ -82,7 +82,7 @@ deps =
     py==1.4.27
     pytest==2.7.1
     pyflakes==0.9.0
-    pytest-flakes==0.2
+    pytest-flakes==1.0.0
 commands =
     {[testenv:mkvenv]commands}
     {envpython} -m py.test -q --flakes -m flakes