Fixes #3131 - Output information at the end of the foreman-installer

Produces output like:

```
# foreman-installer
  Success!
    You can now login at https://test.domain.org
    A proxy is running at https://test.domain.org:8443
    A puppetmaster has been set up on port 8140
  There is a full log /var/log/foreman-installer/foreman-installer.log
```

or on error:

```
# foreman-installer
  Something went wrong! Check the log below for ERROR level lines
  There is a full log /var/log/foreman-installer/foreman-installer.log
```