Add support for FreeBSD next generation package manager
Refactor FreeBSD package providers
Refactor resolving of Freebsd package provider
Access source instance variable directly when setting provider
Merge branch 'freebsdPkgngSupport' of github.com:liseki/chef

Conflicts:
	lib/chef/platform/provider_mapping.rb
Contribution info for CHEF-4637.
Merge branch 'master' into sersut/CHEF-4637

Conflicts:
	CHANGELOG.md
Merge pull request #1421 from opscode/sersut/CHEF-4637

CHEF-4637 - Add support for the new generation FreeBSD package manager