Incorporate fixes for format-secondary-disk script introduced in centos 2.6.0 image. Partially addresses IMAGE-446.
Incorporate fixes for format-secondary-disk script introduced in centos
2.6.0 image. Partially addresses IMAGE-446.

joyent/sdc-vmtools-lx-brand,joyent/sdc-vmtools,rcj4747/sdc-vmtools-lx-brand