Add missing variable for cloud-config interpolation
Add missing variable for cloud-config interpolation

[#140698333](https://www.pivotaltracker.com/story/show/140698333)

Signed-off-by: Dennis Leon <84f467a5e250ceeacb4292b28bf3ac3f822ea696@pivotal.io>

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh