Add migration to retroactively convert HttpLogs to UTF8

db/migrate/20180711080554_issue_2100_utf8_encode_http_logs.rb

@@ -0,0 +1,11 @@
+class Issue2100Utf8EncodeHttpLogs < ActiveRecord::Migration[5.1]
+  def up
+    HttpLog.where('request LIKE :enctag OR response LIKE :enctag', enctag: '%content: !binary |%')
+           .limit(100_000)
+           .order(created_at: :desc)
+           .find_each do |log|
+             log.update(request: log.request.transform_values(&:utf8_encode),
+                        response: log.response.transform_values(&:utf8_encode))
+           end
+  end
+end