hack/cluster: consolidate cluster/ utils to hack/lib/util.sh

Per Clayton's suggestion, move stuff from cluster/lib/util.sh to
hack/lib/util.sh.  Also consolidate ensure-temp-dir and use the
hack/lib/util.sh implementation rather than cluster/common.sh.

hack/lib/util.sh

@@ -694,6 +694,35 @@ EOF
   fi
 }
 
+# Wait for background jobs to finish. Return with
+# an error status if any of the jobs failed.
+kube::util::wait-for-jobs() {
+  local fail=0
+  local job
+  for job in $(jobs -p); do
+    wait "${job}" || fail=$((fail + 1))
+  done
+  return ${fail}
+}
 
+# kube::util::join <delim> <list...>
+# Concatenates the list elements with the delimiter passed as first parameter
+#
+# Ex: kube::util::join , a b c
+#  -> a,b,c
+function kube::util::join {
+  local IFS="$1"
+  shift
+  echo "$*"
+}
+
+# Some useful colors.
+if [[ -z "${color_start-}" ]]; then
+  declare -r color_start="\033["
+  declare -r color_red="${color_start}0;31m"
+  declare -r color_yellow="${color_start}0;33m"
+  declare -r color_green="${color_start}0;32m"
+  declare -r color_norm="${color_start}0m"
+fi
 
 # ex: ts=2 sw=2 et filetype=sh