Fix greencheck multi response

[fershad]

This PR fixes the response for green hosting checks when an array of domains are provided.

Previously, this check returned an empty array []. This was caused by a couple of factors:

• In node, there was an unexported module which was being used to parse results. This resulted in an error being thrown, for which the response was to return a [].
• In esm, there was logging in place which read the API response. Since the response was already used, when the library tried to access it an error would be thrown. This again returned a [] response.

This PR fixes both of those errors. It also updates some of the tests to use the API, rather than a local database.

[fershad]

I also deleted an old readme file in the src directory (https://github.com/thegreenwebfoundation/co2.js/pull/123/files#diff-9ca8f47f3b7fb128a4427ac4122e36ec1efc645ba984bac232c62d3a8d0d2571), since the content it out of date and has been superseded by the developer docs website.