Akismet checker is using 127.0.0.1, not the real IP

GitLab.com is checking spammers against 127.0.0.1, not the real IP. In api/issues.rb, env['REMOTE_ADDR'] is being used. Do we need to use something like this?

request.env['HTTP_X_FORWARDED_FOR'] || request.remote_ip

/cc: @twk3