Feature: Conversation Continuity with Email (#770)

* Added POC for mail inbox reply email
* created mailbox and migratuion for the same
* cleaned up sidekiq queues and added the queues for action mailbox and active storage
* created conversation mailbox and functionlaity to create a message on the conversation when it's replied

* Added UUID to conversation to be used in email replies

* added migration to add uuid for conversation
* changed parsing and resource fetching to reflect matching uuid and
  loading conversation alone
* cleaned up conversation mailbox.rb

* Added content type & attribute for message

* Added the new reply email to outgoing emails
* Added migration to accounts for adding domain and settings
* Modified seeds to reflect this changes
* Added the flag based column on account for boolean settings
* Added the new reply to email in outgoing conversation emails based on conditions

* Added dynamic email routing in application mailbox
* Added dynamic email routing in application mailbox
* Added a catch all deafult empty mailbox
* Added annotation for account

* Added the complete email details & attachments to the message
* Added the complete email details to the message in content_attributes, like subject, to, cc, bcc etc
* Modified the mail extractor to give a serilaized version of email
* Handled storing attachments of email on the message

* Added incoming email settings, env variables

* [#138] Added documentation regarding different email settings and variables

* Fixed the mail attachments blob issue (#138)
* Decoided attachments were strings and had to construct blobs out fo them to work with active storage
* Fixed the content encoding issue with mail body
* Fixed issue with Proc used in apllication mailbox routing
* Fixed couple of typos and silly mistakes

* Set appropriate from email for conversation reply mails (#138)
* From email was taken from a env variable, changed it to take from account settings if enabled
* Set the reply to email correctly based on conversation UUID
* Added commented config ind development.rb for mailbox ingress

* Added account settings for domain and support email (#138)
* Added the new attributes in accounts controller params whitelisting, api responses
* Added options for the the new fields in account settings

* Fixed typos in email continuity docs and warnings

* Added specs for conversation reply mailer changes (#138)
* Added specs for
  * conversation reply mailer
  * Accounts controller
  * Account and Conversation models

* Added tests for email presenter (#138)

* Specs for inbound email routing and mailboxes (#138)

config/environments/development.rb

@@ -1,6 +1,9 @@
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
+  # set this to appropriate ingress channel when you are doing development in local with regards to incoming emails
+  # config.action_mailbox.ingress = :sendgrid
+
   # In the development environment your application's code is reloaded on
   # every request. This slows down response time but is perfect for development
   # since you don't have to restart the web server when you make code changes.