move d3 to npm

Gruntfile.js

@@ -31,7 +31,7 @@ module.exports = function(grunt) {
     'js/lib/tinymce.min.js',
     'js/lib/handlebars.js',
     'js/lib/openseadragon.js',
-    'js/lib/d3.v3.min.js',
+    'node_modules/d3/d3.min.js',
     'js/lib/pubsub.min.js',
     'js/lib/URI.min.js',
     'js/lib/mousetrap.min.js',

package.json

@@ -46,6 +46,8 @@
     "test": "./node_modules/.bin/karma start ./karma.conf.js",
     "travis": "./node_modules/grunt-cli/bin/grunt ci --verbose --force & npm run test"
   },
-  "dependencies": {},
+  "dependencies": {
+    "d3": "^3.5.17"
+  },
   "engine": "node < 7.0.0"
 }