download karaf 4.2.1 from maven central

Change-Id: Icb7e0400ee5b34ed4be33afdda5074a6f6ec1f6d
diff --git a/tools/package/onos-prep-karaf b/tools/package/onos-prep-karaf
index b77d7e6..468494f 100755
--- a/tools/package/onos-prep-karaf
+++ b/tools/package/onos-prep-karaf
@@ -6,8 +6,7 @@
 set -eu -o pipefail
 
 OUT=$1
-#export HOME=/Users/tom
-KARAF_TAR="$HOME/Downloads/apache-karaf-4.2.1.tar.gz"
+KARAF_TAR=$2
 ONOS_VERSION=$3
 BRANDING=$4
 KARAF_PATCHES=$5