python3 compatible serpent

Author: pipermerriam

dev_requirements.txt

@@ -3,4 +3,7 @@ coveralls
 pytest>=2.9.0
 pytest-catchlog==1.2.2
 pytest-timeout==1.0.0
-https://github.com/ethereum/serpent/tarball/develop
+# This needs https://github.com/ethereum/serpent/pull/102 to be merged so for
+# python3 compat with serpent.
+#https://github.com/ethereum/serpent/tarball/develop
+https://github.com/pipermerriam/serpent/tarball/piper/add-travis-ci-testing