Consistently treat tinyint(1) fields in message database as booleans (#2380)

* Update mysql2 query call to cast booleans

* Treat messages:held field as boolean

* Treat messages:inspected field as boolean

* Treat messages:spam field as boolean

* Treat messages:threat field as boolean

* Treat messages:bounce field as boolean

* Treat messages:received_with_ssl field as boolean

* Treat deliveries:sent_with_ssl field as boolean

app/controllers/messages_controller.rb

@@ -153,7 +153,7 @@ class MessagesController < ApplicationController
 
   def get_messages(scope)
     if scope == "held"
-      options = { where: { held: 1 } }
+      options = { where: { held: true } }
     else
       options = { where: { scope: scope, spam: false }, order: :timestamp, direction: "desc" }