add polyfills for browsers without Promises&fetch support

fixes #17

bower.json

@@ -22,6 +22,8 @@
     "tests"
   ],
   "dependencies": {
-    "vega": "^2.6.1"
+    "vega": "^2.6.1",
+    "es6-promise": "^4.0.5",
+    "fetch": "^1.0.0"
   }
 }

bower_components/es6-promise/.bower.json

@@ -0,0 +1,32 @@
+{
+  "name": "es6-promise",
+  "namespace": "Promise",
+  "version": "4.0.5",
+  "description": "A polyfill for ES6-style Promises, tracking rsvp",
+  "authors": [
+    "Stefan Penner <[email protected]>"
+  ],
+  "main": "./es6-promise.js",
+  "keywords": [
+    "promise"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/stefanpenner/es6-promise.git"
+  },
+  "bugs": {
+    "url": "https://github.com/stefanpenner/es6-promise/issues"
+  },
+  "license": "MIT",
+  "homepage": "https://github.com/components/es6-promise",
+  "_release": "4.0.5",
+  "_resolution": {
+    "type": "version",
+    "tag": "v4.0.5",
+    "commit": "0fb91f2712bebe86121aa0ece486f8bcf346ba0a"
+  },
+  "_source": "https://github.com/components/es6-promise.git",
+  "_target": "^4.0.5",
+  "_originalSource": "es6-promise",
+  "_direct": true
+}

bower_components/es6-promise/bower.json

@@ -0,0 +1,21 @@
+{
+  "name": "es6-promise",
+  "namespace": "Promise",
+  "version": "4.0.5",
+  "description": "A polyfill for ES6-style Promises, tracking rsvp",
+  "authors": [
+    "Stefan Penner <[email protected]>"
+  ],
+  "main": "./es6-promise.js",
+  "keywords": [
+    "promise"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/stefanpenner/es6-promise.git"
+  },
+  "bugs": {
+    "url": "https://github.com/stefanpenner/es6-promise/issues"
+  },
+  "license": "MIT"
+}