update license field in bower.json, multi-select.jquery.json

[Amomo]

Hello, I think multi-select is under the WTFPL license.
README.md needs a update.

[lou]

@Amomo, I updated the license to be under MIT.
Feel free to tell me if it's an issue for you.

[Amomo]

Oh, just want to confirm it with you.
Maybe you can also update the license info in bower.json, multi-select.jquery.json and the website.

[lou]

You are right