Show associated group when sending messages (fixes #559)

config/locales/de.yml

@@ -1407,6 +1407,8 @@ de:
         Antworten: %{reply_url}
         Nachricht online einsehen: %{msg_url}
         Nachrichten-Einstellungen: %{profile_url}
+      footer_group: |
+        Gesendet an Gruppe: %{group}
   model:
     delivery:
       each_stock_article_must_be_unique: Lieferung darf jeden Lagerartikel höchstens einmal auflisten.

config/locales/en.yml

@@ -1432,6 +1432,8 @@ en:
         Reply: %{reply_url}
         See message online: %{msg_url}
         Messaging options: %{profile_url}
+      footer_group: |
+        Sent to group: %{group}
   model:
     delivery:
       each_stock_article_must_be_unique: Each stock article must not be listed more than once.

plugins/messages/app/views/messages_mailer/foodsoft_message.text.haml

@@ -1,4 +1,6 @@
 = raw @message.body
 ======================================================================
 \
+- if @message.group
+  = raw t '.footer_group', group: @message.group.name
 = raw t '.footer', reply_url: new_message_url('message[reply_to]' => @message.id), msg_url: message_url(@message), profile_url: my_profile_url