Let email node be able to send blank topic

and let msg.description be " also
to close #959

social/email/locales/de/61-email.json

@@ -36,7 +36,7 @@
             "always": "immer",
             "rejectUnauthorised": "Überprüfen sie, ob das serverzertifikat gültig ist"
         },
-        "default-message": "__description__\n\nDatei von Node-RED ist angehängt: __filename__",
+        "default-message": "\nDatei von Node-RED ist angehängt: __filename__",
         "tip": {
             "cred": "<b>Hinweis</b>: Berechtigungen von globaler emailkeys.js-Datei kopiert",
             "recent": "Tipp: Es wird nur die letzte E-Mail abgerufen",

social/email/locales/en-US/61-email.json

@@ -42,10 +42,10 @@
             "keyFile":"Private key",
             "users": "Users",
             "auth": "Authenticate users",
-            "addButton": "Add",   
+            "addButton": "Add",
             "expert": "Expert"
         },
-        "default-message": "__description__\n\nFile from Node-RED is attached: __filename__",
+        "default-message": "\nFile from Node-RED is attached: __filename__",
         "tip": {
             "cred": "<b>Note:</b> Copied credentials from global emailkeys.js file.",
             "recent": "Tip: Only retrieves the single most recent email.",

social/email/locales/ja/61-email.json

@@ -36,7 +36,7 @@
             "always": "常時",
             "rejectUnauthorised": "チェックサーバ証明書は有効です"
         },
-        "default-message": "__description__\n\nNode-REDからファイルが添付されました: __filename__",
+        "default-message": "\nNode-REDからファイルが添付されました: __filename__",
         "tip": {
             "cred": "<b>注釈:</b> emailkeys.jsファイルから認証情報をコピーしました。",
             "recent": "注釈: 最新のメールを1件のみ取得します。",