Since the package-installs-squash script relies on the defined
environment variables for figuring out what the values are for an
element's install type and the default install types, sudo -E must be
used to preserve the environment.
Change-Id: Ice5cf0bca65d8078f84daedbef123fc73d5a7b63
Instead of doing the work in the image of parsing through the element's
package-install declarations, we can squash it on hostside, where we
have both YAML and JSON available to us, and then emit a single
pre-processed file into the target to be used later.
Change-Id: I3f182aa3aae0a79b2f3ea4e66c1878ad12878b0a