6819770 ipsilon-server-install: Use input() from six for Python 3 compatibility

Authored and Committed by ngompa 3 years ago
    ipsilon-server-install: Use input() from six for Python 3 compatibility
    
    In Python 3, raw_input() was renamed to input() as a breaking change.
    Adapt to this by using six to have input() working properly on Py2 and Py3.
    
    Signed-off-by: Neal Gompa <ngompa13@gmail.com>