Make cyphernode apps repo configurable in setup

[kumulynja]

Currently the apps repo https://github.com/SatoshiPortal/cypherapps is hardcoded in the setup file.
It would be good during the setup to ask if this default apps repo should be used or another repo should be cloned.
Like this one can create its own cyphernode apps repo and still use the original cyphernode repo without forking or changing the hardcoded value locally.