[ci] Upgrade pip, setuptools and wheel before build

Attempt to speed up the build on travis-ci

Author: nemesifier

.travis.yml

@@ -17,6 +17,7 @@ branches:
 # perform static analysis before installing all dependencies
 # this allows to save resources and build time if this step fails
 before_install:
+  - pip install -U pip setuptools wheel
   - pip install --no-cache-dir -U -r requirements-test.txt
   - ./runflake8
   - if [[ $TRAVIS_PYTHON_VERSION == 3* ]]; then ./runisort; fi