temporarily removed pypy3 from travis since build is failing due to permission issue

.travis.yml

@@ -4,7 +4,6 @@ python:
   - "3.4"
   - "2.7"
   - "pypy"
-  - "pypy3"
 
 # command to install dependencies, e.g. pip install -r requirements.txt --use-mirrors
 install: pip install -r requirements-dev.txt