add gocrawl tag in the "browser" user-agent string, closes #41
add gocrawl tag in the "browser" user-agent string, closes #41

vizewang/gocrawl,fjordan/gocrawl,PuerkitoBio/gocrawl,mantyr/gocrawl,fjordan/gocrawl,mantyr/gocrawl,vizewang/gocrawl