Create npm build scripts that use webpack to build UMD bundle

npm scripts:
- build (unminified UMD bundle)
- build-min (minified UMD bundle)

`webpack.config.js`:
- Remove "entry" and "output.filename" now that paths are passed
  via CLI

Author: remarkablemark

package.json

@@ -5,6 +5,8 @@
   "author": "Mark <mark@remarkablemark.org>",
   "main": "index.js",
   "scripts": {
+    "build": "webpack index.js dist/html-to-react.js",
+    "build-min": "webpack -p index.js dist/html-to-react.min.js",
     "test": "mocha",
     "lint": "eslint index.js \"lib/**\" \"test/**\"",
     "cover": "istanbul cover _mocha -- -R spec \"test/**/*\"",

webpack.config.js

@@ -4,9 +4,7 @@
  * Export webpack configuration.
  */
 module.exports = {
-    entry: './index',
     output: {
-        filename: './dist/html-to-react.min.js',
         library: 'HTMLReactParser',
         libraryTarget: 'umd'
     },