Update dependencies

Update the request header to make the library more reliable.

Use the new API of leboncoin.fr

thanks @alcaneo and @myrevers

Fix Seller name for professional Seller

Thanks @Alexandre3721

It's now possible to search on leboncoin with a specific url like this:

var url = 'http://www.leboncoin.fr/ventes_immobilieres/offres/...';
new leboncoin.Search().run(url).then(function (data) {
  console.log(data);
});

If url is null, the library will use the previous API.

Fix

• Adpats the parsers to the new leboncoin website

Fix

• Fix the image parser

This revision fixes the issue #8.