[COOK-2563] Installation fails when we have a dirty '/var/lib/alternatives/#{cmd}'

https://tickets.opscode.com/browse/COOK-2563

The install will fail if `update-alternatives --display` shows no reference of a given command but there is one in `/var/lib/alternatives`. Apparently this might be caused by a previous install of a package.
To fix the problem we need to remove any reference of the command in `/var/lib/alternatives`.