Update translations.php

Bran -> Surely a typo
Braun (Amber) -> Bernstein is actually the literal translation of amber and used for the color as well.
Lime -> With several shades of green, I think Giftgrün fits more than describing it with the english term.
Zuständig -> would be an adjective, Zuständiger is a person.

app/Locale/de_DE/translations.php

@@ -20,15 +20,15 @@ return array(
     'Red' => 'Rot',
     'Orange' => 'Orange',
     'Grey' => 'Grau',
-    'Brown' => 'Bran',
+    'Brown' => 'Braun',
     'Deep Orange' => 'Dunkelorange',
     'Dark Grey' => 'Dunkelgrau',
     'Pink' => 'Pink',
     'Teal' => 'Türkis',
     'Cyan' => 'Cyan',
-    'Lime' => 'Grün (lime)',
+    'Lime' => 'Giftgrün',
     'Light Green' => 'Hellgrün',
-    'Amber' => 'Braun  (Amber)',
+    'Amber' => 'Bernstein',
     'Save' => 'Speichern',
     'Login' => 'Anmelden',
     'Official website:' => 'Offizielle Webseite:',
@@ -96,7 +96,7 @@ return array(
     'Edit a task' => 'Aufgabe bearbeiten',
     'Column' => 'Spalte',
     'Color' => 'Farbe',
-    'Assignee' => 'Zuständig',
+    'Assignee' => 'Zuständiger',
     'Create another task' => 'Weitere Aufgabe erstellen',
     'New task' => 'Neue Aufgabe',
     'Open a task' => 'Öffne eine Aufgabe',