onos-* script help functions, plus:

o support onos-watch on OS X by emulating 'watch'.

Change-Id: I072f347b21b038168e08405bd228434bcc421aeb
diff --git a/tools/test/bin/onos-archetypes-test b/tools/test/bin/onos-archetypes-test
old mode 100755
new mode 100644
index 7ae0033..331c433
--- a/tools/test/bin/onos-archetypes-test
+++ b/tools/test/bin/onos-archetypes-test
@@ -3,6 +3,19 @@
 # Builds a set of projects using ONOS archetypes.
 # -----------------------------------------------------------------------------
 
+function _usage () {
+cat << _EOF_
+usage:
+ $(basename $0)
+
+summary:
+ Builds a set of projects using ONOS archetypes.
+
+_EOF_
+}
+
+[ "$1" = "-h" ] && _usage && exit 0
+
 set -e
 
 export AROOT=/tmp/foo