download karaf 4.2.1 from maven central

Change-Id: Icb7e0400ee5b34ed4be33afdda5074a6f6ec1f6d
diff --git a/tools/build/envDefaults b/tools/build/envDefaults
index 09e6979..5b7880a 100644
--- a/tools/build/envDefaults
+++ b/tools/build/envDefaults
@@ -5,7 +5,7 @@
 
 # M2 repository and Karaf gold bits
 export M2_REPO=${M2_REPO:-~/.m2/repository}
-export KARAF_VERSION=${KARAF_VERSION:-3.0.8}
+export KARAF_VERSION=4.2.1
 export KARAF_ZIP=${KARAF_ZIP:-~/Downloads/apache-karaf-$KARAF_VERSION.zip}
 export KARAF_TAR=${KARAF_TAR:-~/Downloads/apache-karaf-$KARAF_VERSION.tar.gz}
 export KARAF_DIST=$(basename $KARAF_ZIP .zip)