add mongo test case: auth

examples/main_mongodb.lua

@@ -0,0 +1,12 @@
+local skynet = require "skynet"
+
+
+skynet.start(function()
+	print("Main Server start")
+	local console = skynet.newservice(
+		"testmongodb", "127.0.0.1", 27017, "testdb", "test", "test"
+	)
+	
+	print("Main Server exit")
+	skynet.exit()
+end)