feat(poster.go): post function to post a command

  Post("where", url.Values{"example": "Example"}) returning HTTP
response.

go.mod

@@ -0,0 +1,3 @@
+module red-green/go-roku
+
+go 1.17

poster.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"net/url"
+)
+
+func Post(where string, data *url.Values) *http.Response {
+	resp, err := http.PostForm(where, *data)
+	if err != nil {
+		log.Fatalf("POST got non 200 code, %v", err)
+	}
+	return resp
+}