add library files for socat in mkimage-unittest.sh

in https://docs.docker.com/articles/ambassador_pattern_linking/
svendowideit/ambassador images is from docker-ut built using this script
and uses socat but socat complains as follows
socat: error while loading shared libraries: libreadline.so.5: cannot open shared object file: No such file or directory
socat: error while loading shared libraries: libssl.so.1.0.0: cannot open shared object file: No such file or directory
socat: error while loading shared libraries: libcrypto.so.1.0.0: cannot open shared object file: No such file or directory
socat: error while loading shared libraries: libtinfo.so.5: cannot open shared object file: No such file or directory
/usr/lib/x86_64-linux-gnu/lib{crypto,ssl}.so* lib are symlinks so removing -P option from cp
adding libreadline.so and libtinfo.so

Signed-off-by: Jinsoo Park <cellpjs@gmail.com>

update libssl.so path

Signed-off-by: Jinsoo Park <cellpjs@gmail.com>

Remove mkimage-unittest.sh

Signed-off-by: Jinsoo Park <cellpjs@gmail.com>

contrib/mkimage-unittest.sh

@@ -1,49 +0,0 @@
-#!/usr/bin/env bash
-# Generate a very minimal filesystem based on busybox-static,
-# and load it into the local docker under the name "docker-ut".
-
-missing_pkg() {
-    echo "Sorry, I could not locate $1"
-    echo "Try 'apt-get install ${2:-$1}'?"
-    exit 1
-}
-
-BUSYBOX=$(which busybox)
-[ "$BUSYBOX" ] || missing_pkg busybox busybox-static
-SOCAT=$(which socat)
-[ "$SOCAT" ] || missing_pkg socat
-
-shopt -s extglob
-set -ex
-ROOTFS=`mktemp -d ${TMPDIR:-/var/tmp}/rootfs-busybox.XXXXXXXXXX`
-trap "rm -rf $ROOTFS" INT QUIT TERM
-cd $ROOTFS
-
-mkdir bin etc dev dev/pts lib proc sys tmp
-touch etc/resolv.conf
-cp /etc/nsswitch.conf etc/nsswitch.conf
-echo root:x:0:0:root:/:/bin/sh > etc/passwd
-echo daemon:x:1:1:daemon:/usr/sbin:/bin/sh >> etc/passwd
-echo root:x:0: > etc/group
-echo daemon:x:1: >> etc/group
-ln -s lib lib64
-ln -s bin sbin
-cp $BUSYBOX $SOCAT bin
-for X in $(busybox --list)
-do
-    ln -s busybox bin/$X
-done
-rm bin/init
-ln bin/busybox bin/init
-cp -P /lib/x86_64-linux-gnu/lib{pthread*,c*(-*),dl*(-*),nsl*(-*),nss_*,util*(-*),wrap,z}.so* lib
-cp /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 lib
-cp -P /usr/lib/x86_64-linux-gnu/lib{crypto,ssl}.so* lib
-for X in console null ptmx random stdin stdout stderr tty urandom zero
-do
-    cp -a /dev/$X dev
-done
-
-chmod 0755 $ROOTFS # See #486
-tar --numeric-owner -cf- . | docker import - docker-ut
-docker run -i -u root docker-ut /bin/echo Success.
-rm -rf $ROOTFS