demo script updates (#934)

Demo script updates.  Record-replay, a bugfix in the canary demo script, etc.

demos/declarative-specs/hello.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"net/http"
+)
+
+// Handler is the entry point for this fission function
+
+func Handler(w http.ResponseWriter, r *http.Request) {
+	msg := "Hello, CNCF Webinar!\n"
+	w.Write([]byte(msg))
+}