remove use mirrors, depricated

Author: gijzelaerr

.travis.yml

@@ -26,7 +26,7 @@ install:
   - pip install --upgrade pip
   - pip install "sqlalchemy>= 0.8,<1.0"
   - pip install -r requirements.txt
-  - pip install --use-mirrors nose mock coverage
+  - pip install nose mock coverage
   - "./setup.py install"
 script:
   - "./run_tests.py"