Custom attributes in ReactInitJavaScript script tag

[gunnim]

Same as the now closed issue #334

Like the aforementioned post, I'm about to implement CSP on a site using ReactJS.NET.
For the inline script created by ReactInitJavaScript to work i need to add a nonce attribute to the script tag with a value that matches one in my CSP headers.

Currently I have created my own helper, similar in functionality to ReactInitJavaScript.
However, seeing as this configuration might become more and more common as time goes on, I think it might make sense to integrate into the project.

Do you agree?
And yes I'd be willing to submit a pull request :)