Merge project into referer-parser/go

[alexanderdean]

Seems a waste of effort to be maintaining a separate Go codebase and (much less expansive) data file.

https://github.com/snowplow/referer-parser/tree/master/go

[snormore]

@alexanderdean We've been actively using this project in production since before the first commit on snowplow/referer-parser/go, but you're welcome to submit pull requests to converge the two projects :)

EDIT: we'd be happy to work with you on this endeavor, we have an equivalent Python version available that could be converged with yours as well.

[alexanderdean]

Hey @snormore - we'd love to work with you guys on this! The main value of these projects is in the referers database, and the more contributors we can get to those the better. referer-parser is used by Snowplow, Skimlinks and Keen.io, among others.

Functionality-wise, the libs and databases look pretty similar. You have a wildcard concept, which we don't yet have (snowplow-referer-parser/referer-parser#19). I imagine that would be the main barrier to harmonizing.

We have a couple of interesting things which I didn't spot in goreferrer:

1. A JSON-driven set of tests, which is quite nice because all implementations can verify against that JSON
2. A list of "unknown" channel referers. This is a little hacky, but is designed to reduce the number of false positives, so that e.g. support.google.com isn't misidentified as SEARCH

Let's keep the convo going in this ticket - also paging @tsileo and @donspaulding who are the Go and Python maintainers for referer-parser respectively.