Fix case where UID and GID are passed and added a test for that case.

goss.yaml

@@ -1,28 +1,9 @@
-file:
-  /opt/JDownloader/JDownloader.jar:
-    exists: true
-    mode: "0644"
-    filetype: file
-    contains: []
-  /opt/JDownloader/sevenzipjbinding1509.jar:
-    exists: true
-    mode: "0664"
-    filetype: file
-    contains: []
-  /opt/JDownloader/sevenzipjbinding1509Linux.jar:
-    exists: true
-    mode: "0664"
-    filetype: file
-    contains: []
-package:
-  ffmpeg:
-    installed: true
 user:
   jdownloader:
     exists: true
-    uid: 1000
-    gid: 100
+    uid: 1001
+    gid: 101
     groups:
-    - users
+    - jdownloader
     home: []
     shell: /bin/false