Add license field to package files

bower.json

@@ -4,6 +4,7 @@
   "description": "Simple HTML5 Charts using the canvas element",
   "homepage": "https://github.com/nnnick/Chart.js",
   "author": "nnnick",
+  "license": "MIT",
   "main": [
     "dist/Chart.js"
   ],

package.json

@@ -3,6 +3,7 @@
   "homepage": "http://www.chartjs.org",
   "description": "Simple HTML5 charts using the canvas element.",
   "version": "2.0.2",
+  "license": "MIT",
   "main": "src/chart.js",
   "repository": {
     "type": "git",