Refactor settings model

Move the various sections to their own concerns, so they're easier to
find and maintain

app/models/concerns/settings/email_settings.rb

@@ -0,0 +1,28 @@
+module Settings
+  module EmailSettings
+    extend ActiveSupport::Concern
+
+    included do
+      field :email_enabled, type: :boolean,
+        default: ENV["EMAIL_SMTP_HOST"].present?
+
+      # field :email_smtp_host, type: :string,
+      #   default: ENV["EMAIL_SMTP_HOST"].presence
+      #
+      # field :email_smtp_port, type: :string,
+      #   default: ENV["EMAIL_SMTP_PORT"].presence || 587
+      #
+      # field :email_smtp_enable_starttls, type: :string,
+      #   default: ENV["EMAIL_SMTP_PORT"].presence || true
+      #
+      # field :email_auth_method, type: :string,
+      #   default: ENV["EMAIL_AUTH_METHOD"].presence || "plain"
+      #
+      # field :email_imap_host, type: :string,
+      #   default: ENV["EMAIL_IMAP_HOST"].presence
+      #
+      # field :email_imap_port, type: :string,
+      #   default: ENV["EMAIL_IMAP_PORT"].presence || 993
+    end
+  end
+end