Adding set -e to build commands

Change-Id: I72d02db1f6f8484f4ffb2d00406e6af2c866a7fb
diff --git a/tools/build/onos-snapshot b/tools/build/onos-snapshot
index 10da019..e482df9 100755
--- a/tools/build/onos-snapshot
+++ b/tools/build/onos-snapshot
@@ -3,6 +3,8 @@
 # Drives the ONOS snapshot process.
 # -----------------------------------------------------------------------------
 
+set -e
+
 [ ! -d "$ONOS_ROOT" ] && echo "ONOS_ROOT is not defined" >&2 && exit 1
 . $ONOS_ROOT/tools/build/envDefaults