add customHeaders option

[chienwen]

I suggest adding a new option customHeaders to specify any header if needed.

In my use case, a website may prompt a window at the first time to confirm my age is over 18. So in this case I can add a custom cookie in the header:

urlMetadata('https://www.ptt.cc/bbs/Gossiping/index.html', {
    customHeaders: {
        'cookie': 'over18=1'
    }
}).then( ... );

[bieblebrox]

When will this be merged?

[laurengarcia]

Custom header option available in new version 3.0.1 https://www.npmjs.com/package/url-metadata