Temporarily use py3 serpent version from serpent PR

There is sort of a deadlock for getting py3 support between
`ethereum/pyethereum` and `ethereum/serpent`, due to a circular
test dependency. In order to break the circle, this can be used
to create a release, which in turn can be used by `serpent`s build.

see #357

Author: konradkonrad

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/ethereum/serpent/tarball/develop
+https://github.com/pipermerriam/serpent/tarball/piper/add-travis-ci-testing

setup.py

@@ -8,14 +8,14 @@
 install_requires = set(x.strip() for x in open('requirements.txt'))
 install_requires_replacements = {
     'https://github.com/ethereum/ethash/tarball/master': 'pyethash',
-    'git+https://github.com/ulope/secp256k1-py#egg=secp256k1': 'secp256k1'
 }
 install_requires = [install_requires_replacements.get(r, r) for r in install_requires]
 
 # dev requirements
 tests_require = set(x.strip() for x in open('dev_requirements.txt'))
+tests_require_replacements = dict()
 tests_require_replacements = {
-    'https://github.com/ethereum/serpent/tarball/develop': 'ethereum-serpent>=1.8.1',
+    'https://github.com/pipermerriam/serpent/tarball/piper/add-travis-ci-testing': 'ethereum-serpent>=1.8.1'
 }
 tests_require = [tests_require_replacements.get(r, r) for r in tests_require]