Erldns admin API.

Configuration:

This application will read from your sys.config the following example:

{erldns, [
    {admin, [
        {credentials, {<<"username">>, <<"password">>}},
        {port, 8083},
        {middleware, [my_custom_middleware, another_middleware]}
    ]}
]}

where credentials is a tuple of username and password as either strings or binaries, port is a valid Unix port to listen on, and middleware is an optional list of middleware modules that will be applied to all admin API requests.