Fixes issue where lsbdist failure gave unclear message
Adds spec test for when lsbdistid = ''

On machines where lab-release is not installed, it will fail with the following error message:
`Error: Unsupported lsbdistid () at /modules/apt/manifests/params.pp:52 on node`
This commit adds a specific case for when lab-release is not installed providing a clearer error message