Fixes #59, update cask if auto-update is true

Not having homebrew cask updated can lead to problems such as reported
in the following issues. The cask recipe should perform an update if
the auto-update attribute is true.

*
Homebrew/homebrew-cask#7946 (comment)
907
* chef-boneyard/pantry-chef-repo#9

.kitchen.yml

@@ -12,10 +12,12 @@ platforms:
   # https://github.com/timsutton/osx-vm-templates
   # https://github.com/opscode/bento/blob/master/packer/macosx-10.9.json
   - name: macosx-10.9
+  - name: macosx-10.10
 
 suites:
   - name: default
     run_list:
       - recipe[build-essential]
       - recipe[homebrew::default]
+      - recipe[homebrew::cask]
     attributes:

recipes/cask.rb

@@ -16,7 +16,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+extend(Homebrew::Mixin)
+owner = homebrew_owner
 
 homebrew_tap 'caskroom/cask'
 
 package 'brew-cask'
+
+execute 'update homebrew cask from github' do
+  user owner
+  command '/usr/local/bin/brew upgrade brew-cask && /usr/local/bin/brew cask cleanup || true'
+  only_if { node['homebrew']['auto-update'] }
+end