19 Fix duplicate entrees when a single vm has multiple drives with low freespace

Fixed module 19 to handle multiple drives per vm that are low on freespace.

Before: [note the duplicate lines]
![vcheck_disk](https://f.cloud.github.com/assets/4061075/1091184/4b227572-1664-11e3-9db6-7e9366823dab.png)

After:
![vehck_after](https://f.cloud.github.com/assets/4061075/1091185/50240e64-1664-11e3-8709-1c356645fe6b.png)