Refactor and update RocketChat bridge

* Add support for editing/deleting messages
* Add support for uploading files
* Add support for avatars
* Use the Rocket.Chat.Go.SDK
* Use the rest and streaming api

vendor/github.com/nelsonken/gomf/README.md

@@ -0,0 +1,37 @@
+# golang 可多文件上传的request builder 库
+
+## 测试方法
+
+1. start php upload server: php -S 127.0.0.1:8080 ./
+2. run go test -v 
+
+## 使用方法
+
+```go
+	fb := gomf.New()
+	fb.WriteField("name", "accountName")
+	fb.WriteField("password", "pwd")
+	fb.WriteFile("picture", "icon.png", "image/jpeg", []byte(strings.Repeat("0", 100)))
+
+	log.Println(fb.GetBuffer().String())
+
+	req, err := fb.GetHTTPRequest(context.Background(), "http://127.0.0.1:8080/up.php")
+	if err != nil {
+		log.Fatal(err)
+	}
+	res, err := http.DefaultClient.Do(req)
+
+	log.Println(res.StatusCode)
+	log.Println(res.Status)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	b, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println(string(b))
+```