Quick example of a collision test integration test (#265)

* Quick example of a collision test integration test

* Add a test for ghost and hidden sprites

* enable scratch/es6 which then had my lint error for `(param) => {}` arrows

* cleanup npm test command

* an a was an an but should have been an a

* 2space tabs for the html doc

* Add some comments in the integration index html

* Add a few more comments about intentionally leaking variables into the global scope

* add some more comments for the integration helper and add a timeout

* 4 space tabs are actually correct

* adding even more comments and improving readability a little

* fix lint no-shadow rule

* fix indentation on comment

.travis.yml

@@ -1,9 +1,14 @@
 language: node_js
+dist: trusty
+addons:
+  chrome: stable
 node_js:
 - 8
 - node
 env:
   - NODE_ENV=production
+before_install:
+  - google-chrome-stable --headless --no-sandbox --remote-debugging-port=9222 &
 install:
 - npm --production=false install
 - npm --production=false update