Added tox configuration

... and fixed pep8 warnings. There's a lot of them that are still
ignored, but that's because it's too much of a step to take at once.

tox.ini

@@ -0,0 +1,17 @@
+[tox]
+envlist = py33,py34
+skipsdist = True
+
+[testenv]
+commands =
+    flake8
+    py.test core core_se core_me core_pe hscommon
+deps =
+    -r{toxinidir}/requirements.txt
+    -r{toxinidir}/requirements-extra.txt
+
+[flake8]
+exclude = .tox,env,build,hscommon,qtlib,cocoalib,cocoa,help,./get-pip.py,./qt/dg_rc.py,./core*/tests,qt/run_template.py,cocoa/run_template.py,./run.py,./pkg
+max-line-length = 120
+ignore = W391,W293,E302,E261,E226,E227,W291,E262,E303,E265
+