test: add bootstrap file to allow for umd import

Author: keithamus

test/bootstrap.js

@@ -0,0 +1,4 @@
+// Stub out CommonJS for tests
+window.module = {exports: {}}
+window.exports = module.exports
+window.require = Function.prototype

test/karma.config.js

@@ -25,7 +25,7 @@ function reply(request, response, next) {
 module.exports = function(config) {
   config.set({
     frameworks: ['mocha', 'chai'],
-    files: ['../dist/umd/index.js', 'test.js'],
+    files: ['bootstrap.js', '../dist/umd/index.js', 'test.js'],
     reporters: ['mocha'],
     port: 9876,
     colors: true,