Update message for targets in CLI.
Add centos box for testing.
Introduce Base distribution class.
Massive refactoring and reorganization to make place for Redhat-based distros.
RPMs can now be generated.
Force google nameservers in Vagrant.
Put the CLI in /usr/bin on redhat based systems.
Add ubuntu box for testing.
Small changes to centos box.
Outputs buildpack cloning step.
Move slow test to integration.
Added --after-precompile and --license options.
Improve cli message for --force-os option
Fix installation instructions.
Merge branch 'centos'

Massive reorganization of code to make place for Redhat based distributions.
This is still experimental.