Add log_level to Provisioner, Driver, & Busser config.
Fix Provisioner display in `kitchen list`.
Add log level option to `kitchen list`.
Fix output display for `kitchen list --debug`.
Fix Suite & Platform data propagation in Kitchen::Config.
Reference new Provisioner location in Driver::SSHBase#converge.
Major updates to ChefSolo & ChefZero provisioners.

Introduce default config, computed defaults for various Chef data
paths, compute solo.rb and client.rb from a Hash so that settings can be
overridden or added to.