Feat twitch livestreams (#334)

* backend code

* fixed twitch authentication

server/twitch/types.go

@@ -0,0 +1,20 @@
+package twitch
+
+import "time"
+
+type StreamInfo struct {
+	ID        string
+	UserName  string
+	Title     string
+	GameName  string
+	StartedAt time.Time
+	IsLive    bool
+}
+
+type VodInfo struct {
+	ID        string
+	Title     string
+	URL       string
+	Duration  string
+	CreatedAt time.Time
+}