HTTP request User-Agent header styled incorrectly

[midnightfreddie]

When providing a string user agent to the constructor or allowing the default user agent string, it is built as

"headers":{"userAgent":"<user agent string>"}

Servers do not log this header; they show the user agent field as "-". The option needs to be styled as

"headers":{"User-Agent":"<user agent string>"}

Workaround: Pass an object to constructor instead:

var parser = new robots.RobotsParser(
    'http://nodeguide.ru/robots.txt',
    { "headers": { "User-Agent": "My User Agent String" } },
    after_parse
);