update-alternatives doesn't support ruby on 14.04

The tl;dr is that in Ubuntu 14.04, update-alternatives doesn't
actually support `ruby` anymore, so linking the correct binaries in
place must be done "manually." We'll do this with the link resource.
For more background, see this bug report:

* https://bugs.launchpad.net/ubuntu/+source/ruby2.0/+bug/1310292

And this gist:

* https://gist.github.com/jtimberman/1c9cfee514644a04f9c2
add ubuntu 14.04 to kitchen
add postgresql directory

The postgresql directory needs to be created in order for test kitchen
to converge.
Merge pull request #5 from opscode-cookbooks/fix-update-alternatives

update-alternatives doesn't support ruby on 14.04