Run JavaScript tests on Travis

Using Sauce Labs and Grunt. Also install runtime dependencies
using Bower to get the Jed package that's used in testing, and
save the Bower version resolutions for Travis so that step can be
automated.

package.json

@@ -17,8 +17,16 @@
     "eslint": "^1.10.3",
     "eslint-config-airbnb": "^2.0.0",
     "fs-extra": "^0.26.2",
+    "grunt": "^0.4.5",
+    "grunt-cli": "^0.1.13",
+    "grunt-contrib-connect": "^0.11.2",
+    "grunt-contrib-watch": "^0.6.1",
+    "grunt-saucelabs": "^8.6.2",
     "mocha": "^2.3.4",
     "should": "^8.0.1",
     "vulcanize": "^0.7.11"
+  },
+  "scripts": {
+    "test": "grunt test"
   }
 }