Revert to using official serpent library.

Author: pipermerriam

dev_requirements.txt

@@ -3,4 +3,4 @@ coveralls
 pytest>=2.9.0
 pytest-catchlog==1.2.2
 pytest-timeout==1.0.0
-https://github.com/pipermerriam/serpent/tarball/piper/add-travis-ci-testing
+https://github.com/ethereum/serpent/tarball/develop

setup.py

@@ -15,9 +15,7 @@
 # dev requirements
 tests_require = set(x.strip() for x in open('dev_requirements.txt'))
 tests_require_replacements = {
-    # 'https://github.com/ethereum/serpent/tarball/develop': 'ethereum-serpent>=1.8.1',
-    # THIS SHOULD NOT BE MERGED
-    'https://github.com/pipermerriam/serpent/tarball/piper/add-travis-ci-testing': 'ethereum-serpent>=1.8.1',
+    'https://github.com/ethereum/serpent/tarball/develop': 'ethereum-serpent>=1.8.1',
 }
 tests_require = [tests_require_replacements.get(r, r) for r in tests_require]