Deprecation warning for import of flask-basicauth

[rhorst]

Hi,

I'd been getting the following warning repeatedly whenever starting my flask server while working on my app::

1: ExtDeprecationWarning: Importing flask.ext.basicauth is deprecated, use flask
    _basicauth instead.
    .format(x=modname), ExtDeprecationWarning
    * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)

It was really easy to fix - instead of having:: from flask.ext.basicauth import BasicAuth

I had to write:: from flask_basicauth import BasicAuth

However, I noticed that your documentation is a bit out of date and lists the old method of importing an extension. Can I submit a PR and fix this for you?

[jpvanhal]

Sure, go ahead!