Enable configuration of hard eviction thresholds in kubelet.

This will allow for enabling evictions whenever memory availability is
too low.

Signed-off-by: Vishnu kannan <vishnuk@google.com>

cluster/common.sh

@@ -647,6 +647,11 @@ EOF
   if [ -n "${NODE_LABELS:-}" ]; then
       cat >>$file <<EOF
 NODE_LABELS: $(yaml-quote ${NODE_LABELS})
+EOF
+    fi
+  if [ -n "${EVICTION_HARD:-}" ]; then
+      cat >>$file <<EOF
+EVICTION_HARD: $(yaml-quote ${EVICTION_HARD})
 EOF
     fi
   if [[ "${OS_DISTRIBUTION}" == "coreos" ]]; then