Add staypuft-client-installer

Existing staypuft-installer now generates answer file for client
installer. Client installer prepares puppet on target machine and
registers itself in staypuft.

Generates SSH Key for foreman-proxy user and configures the
foreman-proxy service to use puppetssh

It creates foreman .ssh directory and copies the private ssh key
from the foreman-proxy user. This allows DynFlow tasks running as
foreman user to ssh into host machines, allow tasks to test that ssh is
fully configured.