Improved German translation (#129)

* Better German translation of 'valid'.

* Added compiled msg file

jet/dashboard/locale/de/LC_MESSAGES/django.po

@@ -260,7 +260,7 @@ msgid "You must install the FeedParser python module"
 msgstr "Bitte FeedParser Python modul installieren"
 
 msgid "You must provide a valid feed URL"
-msgstr "Bitte eine valide feed URL angeben"
+msgstr "Bitte eine gültige Feed URL angeben"
 
 msgid "Delete widget"
 msgstr "Widget löschen"