feat: fix translations

Author: Angular2Guy

frontend/app/i18n/de/translation.json

@@ -5,7 +5,8 @@
         "message": "Nachricht",
         "language": "Sprache",
         "english": "Englisch",
-        "german": "Deutsch"
+        "german": "Deutsch",
+        "logout": "Abmelden"
     },
     "login": {     
         "username": "Benutzername",

frontend/app/i18n/en/translation.json

@@ -5,7 +5,8 @@
         "message": "Message",
         "language": "Language",
         "english": "English",
-        "german": "German"
+        "german": "German",
+        "logout": "Logout"
     },
     "login": {     
         "username": "Username",