Chef Client 12.6.0 Release

Have Gemspec not always expect chef-config to exist beside it.

Bump revision to 12.5.1

Version tag for 12.4.4

Bump to 12.4.3

Bump revision to 12.1.4

Version tag for 12.5.0.current.0

Merge pull request chef#3654 from chef/tm/11.18.14

Release 11.18.14

Version tag for 12.4.1

Version tag for 12.4.0