ci: Build and install a wheel before all testing

This tests that scuba behaves as expected when installed as a wheel,
which is needed for performance (see #71).

.travis.yml

@@ -31,11 +31,14 @@ before_script:
   - ci/install_musl-libc.sh
   - docker version
   - ci/test_setup.sh
+  - pip install wheel
 
 script:
-  - make
+  # Build and install a wheel
+  # This is the preferred installation mechanism (see #71)
+  - python setup.py bdist_wheel
+  - pip install dist/scuba-$(python -c 'import scuba.version; print scuba.version.__version__')-py2.py3-none-any.whl
   - ./run_nosetests.sh
-  - sudo pip install .
   - ./run_full_tests.py
 
 after_success: