Add iputils-ping to the build scripts

iputils-ping is a required tool for yocto-2.3.

Change-Id: I51834fbc542f88c5f1e673428edb9a56a4f58862
Signed-off-by: Saqib Khan <khansa@us.ibm.com>
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index c2f8275..37c8f28 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -65,7 +65,8 @@
     sudo \
     wget \
     git \
-    dbus
+    dbus \
+    iputils-ping
 
 RUN easy_install pip
 RUN pip install inflection