FEATURE: Replace tkinter from code and change output for CLI/JSON

[dpointk]

If run for CLI

./disko.py
will show menu:

1. Manage Clusters
   a - List cluster
   b - Add/Update Cluster
   c - Delete Cluster
   d - List Current Cluster Registries
2. Manage Target Registries
   a. list registries
   b. add/update
   c. delete
3. more
4. more options