WIP: Exclude networking server specs from vsphere.

Signed-off-by: Mike Stallard <mstallard@pivotallabs.com>
Refactors the vSphere spec exclusion into the builder command.
Excludes aws specific ubuntu specs that break on vSphere.

This adds test coverage for it.

Signed-off-by: Mike Stallard <mstallard@pivotallabs.com>