fixes #4030 - build via librarian-puppet
refs #4030 - use latest dependency modules from git, add mysql
rely on the basename of the script so others can override the location

This change allows katello-installer to use its own configuration file
but re-use the logic contained within foreman-installer.
fixes #4372 - compatibility with Facter 2 API
Refs #3308 - Auto-create mappings hash from detected plugin/compute classes
Remove pl-apache git reference, now 1.0.0 is out
fixes #4301 - specify minimum puppet version of 2.7
Update README.md

Grammar correction
Reuse color support from Kafo

Installer output now uses color scheme selected by user. Also we don't
have to check color configuration manually. HighLine is already set by
Kafo.