Use remote_ip instead of ip (#466)

Correct an issue where the location of users in Mixpanel continues to be wrong.

app/lib/generic_event_tracker.rb

@@ -7,7 +7,7 @@ def self.for_request(request)
       url_params = request.params.slice("client_agency_id", "locale")
       defaults = {
         # Not setting device_id because Mixpanel fixates on that as the distinct_id, which we do not want
-        ip: request.ip,
+        ip: request.remote_ip,
         cbv_flow_id: request.session[:cbv_flow_id],
         client_agency_id: url_params["client_agency_id"],
         locale: url_params["locale"],