Add boxes from VagrantCloud including OS X 10.10
Update homebrew dep.
Bump chef-client version.
Install ruby before git to ensure correct ownership of /usr/local/lib
on OS X.
Mark a few integration tests pending on Mac OS X

ServerSpec 2.0 does not have a full implementation for certain commands
on OS X. Namely `getent` does not exist on OS X so the following error
is thrown:

  /bin/sh: getent: command not found
Merge pull request #61 from opscode-cookbooks/yzl/yosemite

Support OS X 10.10.