Use PhantomJS and enforce singleRun for tests.

Karma previously started a continuous server to allow for multiple
test runs, which would cause `npm test` to hang when tests finish.
This enables the config option `singleRun` so it quits after tests
have finished running.

Additionally, this removes Chrome and the Chrome launcher so tests
can be run properly in a headless environment.

Change-Id: Ib493d9cac3be5a83aa342b0f2a142f82a2757ffb

package.json

@@ -52,7 +52,6 @@
     "karma": "~0.12.0",
     "karma-babel-preprocessor": "^4.0.1",
     "karma-browserify": "^4.0.0",
-    "karma-chrome-launcher": "0.1.8",
     "karma-cli": "0.0.4",
     "karma-coverage": "0.3.1",
     "karma-jasmine": "^0.3.6",

test/karma.conf.js

@@ -12,10 +12,11 @@ module.exports = function(config) {
     preprocessors: {
       'app/js/**/*.js': ['browserify', 'babel', 'coverage']
     },
-    browsers: ['Chrome'],
+    browsers: ['PhantomJS'],
     reporters: ['progress', 'coverage'],
 
     autoWatch: true,
+    singleRun: true,
 
     browserify: {
       debug: true,