Log Message:
Update ruby-mixlib-config to 2.2.4.

2.2.4 (2016-09-02)

* Allow a config context to be set from another config context #42 (mwrock)
* Allow configuring contexts via block #35 (KierranM)

2.2.3 (2016-08-30)

* Dont reset state during restore #40 (mwrock)
* Ignore Gemfile.lock #39 (tas50)
* Update specs for rspec 3.0 #38 (tas50)
* Bump version to 2.2.2 #37 (jkeiser)

2.2.2 (2016-08-22)

* chefstyle fixes #33 (lamont-granquist)
* Add gemspec files to allow bundler to run from the gem #32 (ksubrama)
* Fix ruby warnings #30 (danielsdeleo)