fix config on travis

.travis.yml

@@ -18,7 +18,7 @@ before_install:
 # command to install dependencies, e.g. pip install -r requirements.txt --use-mirrors
 install: 
   - "pip install pymysql"   
-  - "pip install -r requirements.txt"
+  - "pip install -r requirements.txt -r test_requirements"
   - "pip install coveralls"
   - "pip install ."
 # command to run tests, e.g. python setup.py test