Changed routing framework from mux to Gin.

Swagger doc is now included in the application.
A fronted can now be hosted from the application.

pkg/models/models.go

@@ -1,14 +1,16 @@
 package models
 
-import "time"
+import (
+	"time"
+)
 
 type Played struct {
 	Song int
 }
 
 type VersionData struct {
-	Version   string        `json:"version"`
-	Changelog string        `json:"changelog"`
+	Version   string        `json:"version" example:"1.0.0swagger.yaml"`
+	Changelog string        `json:"changelog" example:"account name"`
 	History   []VersionData `json:"history"`
 }