Add blue green deployment example app

blue-green-deploy/environments/default/globals.libsonnet

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+{
+}

blue-green-deploy/environments/default/main.jsonnet

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+local base = import "base.libsonnet";
+// uncomment if you reference ksonnet-lib
+// local k = import "k.libsonnet";
+
+base + {
+  // Insert user-specified overrides here. For example if a component is named \"nginx-deployment\", you might have something like:\n")
+  // "nginx-deployment"+: k.deployment.mixin.metadata.labels({foo: "bar"})
+}

blue-green-deploy/environments/default/params.libsonnet

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+local params = std.extVar("__ksonnet/params");
+local globals = import "globals.libsonnet";
+local envParams = params + {
+  components +: {
+    // Insert component parameter overrides here. Ex:
+    // guestbook +: {
+    //   name: "guestbook-dev",
+    //   replicas: params.global.replicas,
+    // },
+  },
+};
+
+{
+  components: {
+    [x]: envParams.components[x] + globals, for x in std.objectFields(envParams.components)
+  },
+}