Revert "Fix bug 1702 Adding non-root user to run NG-UI"

This reverts commit b147d712.

Reason for revert: NG-UI Container does not start up due to non-root user

nginx: [warn] the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:1
nginx: [emerg] bind() to 0.0.0.0:80 failed (13: Permission denied)

Change-Id: Ibc44fdfe57ca576df70f12f5bb868fe9045990b8
Signed-off-by: beierlm <mark.beierl@canonical.com>