[Feature] Change conversation ordering (#640)

* Update conversation's updated_at when a message is created/saved
* changed teh ordering of conversation to be based on `updated_at` rather than `created_at`

app/models/conversation.rb

@@ -36,7 +36,7 @@ class Conversation < ApplicationRecord
 
   enum status: { open: 0, resolved: 1, bot: 2 }
 
-  scope :latest, -> { order(created_at: :desc) }
+  scope :latest, -> { order(updated_at: :desc) }
   scope :unassigned, -> { where(assignee_id: nil) }
   scope :assigned_to, ->(agent) { where(assignee_id: agent.id) }
 

app/models/message.rb

@@ -51,7 +51,7 @@ class Message < ApplicationRecord
 
   belongs_to :account
   belongs_to :inbox
-  belongs_to :conversation
+  belongs_to :conversation, touch: true
   belongs_to :user, required: false
   belongs_to :contact, required: false