NPM/Browserify support

Please also publish the new versions on NPM via `npm publish`.

This should also resolve https://github.com/angular-translate/angular-translate/issues/255
As the npm webpage can handle this "non conform" type - _maybe_ we could change the license-block to 
```
  "licenses": [
    "type": "MIT",
    "url": "https://github.com/angular-translate/angular-translate/blob/master/LICENSE"
  ]
```

That gives us the possibility to specify the url for our license file in case it ever changes again :-)