TEST: Set up for testing via zuul/sauce labs (#86)

This requires the .travis.yml to be updated with the open sauce credentials
as explained at https://github.com/defunctzombie/zuul/wiki/Travis-ci#5-final-step

README.md

@@ -796,6 +796,18 @@ Consider running some of the following:
 - [envify](https://github.com/hughsk/envify) - replace `process.env` values
   with plain strings
 
+### Choo + Internet Explorer & Safari
+Out of the box `choo` only supports runtimes which support:
+* `const`
+* `fat-arrow` functions (e.g. `() => {}`)
+* `template-strings`
+
+This does not include Safari 9 or any version of IE. If support for these
+platforms is required you will have to provide some sort of transform that
+makes this functionalty available in older browsers.  The test suite uses
+[es2020](https://github.com/yoshuawuyts/es2020) as a global transform, but
+anything else which might satisfy this requirement is fair game.
+
 Generally for production builds you'll want to run:
 ```sh
 $ NODE_ENV=production browserify \
@@ -813,6 +825,13 @@ Yup, it's greatly inspired by the `elm` architecture. But contrary to `elm`,
 ### Is it production ready?
 Sure.
 
+## Browser Test Status
+<a href="https://saucelabs.com/u/yoshuawuyts">
+  <img
+    src="https://saucelabs.com/browser-matrix/yoshuawuyts.svg"
+    alt="Sauce Test Status"/>
+</a>
+
 ## Installation
 ```sh
 $ npm install choo