Support RHEL7 as a default OS for provisioning

When staypuft host is RHEL6 then we automatically configure
RHEL7 as a default OS for provisioning.
On RHEL setup both 6 and 7
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.
Sets up puppetssh

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

Override StrictHostKeySetting for foreman-proxy user
Spec update and version bump
Add missing ssh_keygen module