Improve EIDL functionality

[cmutel]

The EcoinventDownloader is an amazing utility which shouldn't have to exist. We need to either improve the existing code, or integrate its functionality into bw2io, such that:

• The authentication is independent of accessing specific data
• It uses the unique version identifiers
• It can download other information, not just database releases
• It can extract data to use-specified paths, not just temporary directories