Add index file for npm package

package.json

@@ -4,6 +4,7 @@
   "description": "Vue wrapper for chart.js",
   "author": "Jakub Juszczak <jakub@nextindex.de>",
   "private": true,
+  "main": "src/index.js",
   "scripts": {
     "dev": "node build/dev-server.js",
     "build": "node build/build.js",

src/index.js

@@ -0,0 +1,17 @@
+import Bar from './BaseCharts/Bar'
+import Doughnut from './BaseCharts/Doughnut'
+import Line from './BaseCharts/Line'
+import Pie from './BaseCharts/Pie'
+import PolarArea from './BaseCharts/PolarArea'
+import Radar from './BaseCharts/Radar'
+
+const VueCharts = {
+  Bar,
+  Doughnut,
+  Line,
+  Pie,
+  PolarArea,
+  Radar
+}
+
+module.exports = VueCharts