mktarball.sh utility added to 2.0.0 as well

utils/mktarball.sh

+#!/bin/sh
+
+if [ "$1" = "" ]
+then
+    echo "Usage: mktarball.sh <git tag, branch or commit>"
+    echo "Example: mktarball.sh 2.2-rc4"
+    exit 1
+fi
+
+PREFIX="redis-${1}/"
+TARBALL="/tmp/redis-${1}.tar.gz"
+git archive --format=tar --prefix=$PREFIX $1 | gzip -c > $TARBALL
+echo "File created: $TARBALL"