Fix broken dependencies

This is a quick fix to checkout the latest tag of N2VC (BUILD_v4.0.1_1).
Recent commits reveal that some Dockerfiles are using master, instead of
the most recent release, which has caused the install to fail due to
changes in master.

Change-Id: I31280a976d9be2acccca1c75e5b86afeac58e8ee
Signed-off-by: Adam Israel <adam.israel@canonical.com>