Add travis CI (#1)

Add Travis CI support
Run flake8 on py27, py34, py35
diff --git a/tox.ini b/tox.ini
index 1ed7e5c..c1ecf7f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,6 +7,11 @@
 skipsdist = True
 envlist = py35,py34,py27,pypy,pep8
 
+[tox:travis]
+2.7 = py27
+3.4 = py34
+3.5 = py35
+
 [testenv]
 install_command = pip install --allow-external -U {opts} {packages}
 deps =