When using 'make USE_PROXY=true', the 'docker build' is executed with
the correct proxy-related build-args, but the Dockerfile does not
actually consume them.
This change updates the Dockerfiles to accept the following ARGs:
HTTP_PROXY, HTTPS_PROXY, NO_PROXY (upper or lowercase)
Change-Id: I6888d1f15f430e73338c269784ded9a0dea6c9ce