configure travis to generate wheel artifacts

[rosskarchner]

This configures Travis so that whenever a new Github 'release' is created, a wheel is generated and attached to the release page. Here's an example of what that looks like, from college-costs: https://github.com/cfpb/college-costs/releases/tag/2.3.9

Some benefits: this should make deployments faster and simpler (since the package will never need to be "built" in Jenkins), and removes the requirement that every app must support whatever Node version that cfgov-refresh depends on.

You can see in optional-public that we've started replacing git checkout URL's with absolute links to the built wheels: https://github.com/cfpb/cfgov-refresh/blob/master/requirements/optional-public.txt

Additions

• added a script line that generates a Wheel at the end of the test script, and
• 'deploy' configuration in .travis.yml, that (on a new release) will attach the wheel to the release page on Github, as documented here

Changes

• setup.py wasn't responding to bdist_wheel for some reason, I'm not sure-- Switching from distutils to setuptools worked, though

Testing

• As long as Travis gets to the end of the test script, we should be good.

Checklist

• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows the standards laid out in the front end playbook
• Passes all existing automated tests
• New functions include new tests
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged
• Visually tested in supported browsers and devices
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)

[chosak]

Very nice.