GUI -- Added another demo sprite definition file.

Change-Id: I2c7a8b5dd3e3817b1f1e1a91a4ef5d9953a8a283

+{
+  "defn_name": "demo-clouds",
+  "defn_desc": "Demo Sample Subnet Clouds",
+
+  "_comment": [
+    "Sample cloud sprite layout",
+    "(1) Register on the server with ...",
+    "    onos-upload-sprites localhost demo-clouds.json",
+    "(2) Load into topology view with ...",
+    "    http://localhost:8181/onos/ui/index.html#/topo?sprites=demo-clouds"
+  ],
+
+  "paths": [
+    {
+      "tag": "dotted-cloud",
+      "stroke": {
+        "width": 0.8,
+        "dasharray": [2,2]
+      },
+      "glyph": "cloud"
+    }
+  ],
+
+  "defn": [
+    {
+      "id": "subnetA",
+      "path": "dotted-cloud",
+      "dim": [400,400],
+      "labelyoff": 0.85
+    }
+  ],
+
+  "load": {
+    "sprites": [
+      { "id": "subnetA", "pos":[250,40], "label":"192.168.2/24", "class":"blue1" },
+      { "id": "subnetA", "pos":[-200,400], "label":"192.168.1/24", "class":"gold1" },
+      { "id": "subnetA", "pos":[700,400], "label":"192.168.3/24", "class":"gold1" }
+    ],
+    "labels": [
+      { "pos":[450,700], "text":"Demo Subnets", "size":1.6 }
+    ]
+  }
+
+}