Travis: upgrade pip and setuptools at start of build

Hoping to clean up some warnings while installing dependencies.

.travis.yml

@@ -46,6 +46,7 @@ matrix:
     - python: "pypy"
       env: DJANGO=django==1.8
 install:
+  - pip install --upgrade setuptools pip
   - pip install -q $DJANGO
   - pip install .
 script: python -Wall setup.py test