fix: Preserve env variables during 'install.sh'
fix: Preserve env variables during 'install.sh'

When running 'install.sh' with proxy environment variables it is
necessary to use '-E' with sudo to preserve variables. This only affects
the pip commands that require sudo.

Change-Id: I28550b615b11e4635c086569caefbfa09c99c666

open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis