Split logic among more hooks

This makes first wizard to remember answers from previous installation.
It detect default values for the first time.

These changes requires kafo >= 0.6.0 to work.
Update README.md
Merge pull request #5 from ares/remember_values

Remember values
Sets up puppetssh

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