add HA wordpress bundle

redundantwp_bundle.yaml

+series: bionic
+applications:
+  wordpress:
+    charm: "/home/ubuntu/wordpress"
+    num_units: 3
+    to: [ "0", "1", "2" ]
+  percona-cluster:
+    charm: cs:percona-cluster-279
+    num_units: 3
+    to: [ "0", "1", "2" ]
+  haproxy:
+    charm: cs:haproxy
+    num_units: 3
+    to: [ "0", "1", "2" ]
+    expose: true
+    options:
+      peering_mode: active-active
+machines:
+  "0": {}
+  "1": {}
+  "2": {}
+relations:
+- - wordpress:database
+  - percona-cluster:db
+- - wordpress:website
+  - haproxy:reverseproxy