WIP: Add flannel pattern.

+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - https://github.com/coreos/flannel/raw/master/Documentation/kube-flannel.yml
+

+flannel:
+  enabled: true
+cfg: {}

+bases:
+  - ../common/environments.yaml
+
+---
+releases:
+  - name: flannel
+    chart: charts/flannel
+    condition: flannel.enabled
+    strategicMergePatches:
+      - apiVersion: v1
+        kind: ConfigMap
+        metadata:
+          namespace: kube-flannel
+          name: kube-flannel-cfg
+        data:
+          {{ $.Values.cfg | toYaml | nindent 12 }}
+