Add force-confdef in debian package install

In certain cases, with packages cached that need an upgrade,
when performing that action the system hangs waiting for
a prompt.
Add force-confdef option, that will let dpkg overwrite
configuration packages that were not modified. In combination
with already existing force-confold flag, it will allow
to avoid any conffile prompt.

Change-Id: Ifb177f9ac2c9ad29f8b92309c5b8cfe8e60a4e14

elements/dpkg/bin/install-packages

@@ -40,7 +40,8 @@ install_deb_packages () {
     DEBIAN_FRONTEND=noninteractive \
         http_proxy=${http_proxy:-} https_proxy=${https_proxy:-} \
         no_proxy=${no_proxy:-} \
-        apt-get --option "Dpkg::Options::=--force-confold" --assume-yes "$@"
+        apt-get --option "Dpkg::Options::=--force-confold" \
+        --option "Dpkg::Options::=--force-confdef" --assume-yes "$@"
 }
 
 TEMP=$(getopt -o hudem: -n $SCRIPTNAME -- "$@")