FEATURE: add hidden setting for verbose auth token logging

This is only needed to debug auth token issues, will result in lots
of logging

db/migrate/20170213180857_add_user_auth_token_log.rb

@@ -0,0 +1,13 @@
+class AddUserAuthTokenLog < ActiveRecord::Migration
+  def change
+    create_table :user_auth_token_logs do |t|
+      t.string :action, null: false
+      t.integer :user_auth_token_id
+      t.integer :user_id
+      t.inet :client_ip
+      t.string :user_agent
+      t.string :auth_token
+      t.datetime :created_at
+    end
+  end
+end