Implement make dist target

Add dist target to create project tarball. It uses a script called
version, that was obtained from vpp source code to produce a version
string using `git describe` that is incremental based on last annotated
tag available.

extras/scripts/version

@@ -0,0 +1,53 @@
+#!/bin/bash
+#
+# Obtained from VPP - https://wiki.fd.io/view/VPP
+#
+
+path=$( cd "$(dirname "${BASH_SOURCE}")" ; pwd -P )
+
+cd "$path"
+
+if [ -f .version ]; then
+    vstring=$(cat .version)
+else
+    vstring=$(git describe)
+    if [ $? != 0 ]; then
+      exit 1
+    fi
+fi
+
+TAG=$(echo ${vstring} | cut -d- -f1 | sed -e 's/^[vR]//')
+ADD=$(echo ${vstring} | cut -s -d- -f2)
+
+git rev-parse 2> /dev/null
+if [ $? == 0 ]; then
+    CMT=$(git describe --dirty | cut -s -d- -f3,4)
+else
+    CMT=$(echo ${vstring} | cut -s -d- -f3,4)
+fi
+CMTR=$(echo $CMT | sed 's/-/_/')
+
+if [ -n "${BUILD_NUMBER}" ]; then
+       BLD="~b${BUILD_NUMBER}"
+fi
+
+if [ "$1" = "rpm-version" ]; then
+  echo ${TAG}
+  exit
+fi
+
+if [ "$1" = "rpm-release" ]; then
+  [ -z "${ADD}" ] && echo release && exit
+  echo ${ADD}${CMTR:+~${CMTR}}${BLD}
+  exit
+fi
+
+  if [ -n "${ADD}" ]; then
+    if [ "$1" = "rpm-string" ]; then
+      echo ${TAG}-${ADD}${CMTR:+~${CMTR}}${BLD}
+    else
+      echo ${TAG}-${ADD}${CMT:+~${CMT}}${BLD}
+    fi
+  else
+    echo ${TAG}-release
+fi