Changed routing framework from mux to Gin.

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

go.mod

@@ -3,7 +3,15 @@ module music-server
 go 1.16
 
 require (
-	github.com/gorilla/mux v1.8.0
+	github.com/gin-contrib/static v0.0.1
+	github.com/gin-gonic/gin v1.7.7
+	github.com/go-playground/validator/v10 v10.10.0 // indirect
 	github.com/jackc/pgtype v1.5.0
 	github.com/jackc/pgx/v4 v4.9.0
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mattn/go-isatty v0.0.14 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	golang.org/x/crypto v0.0.0-20220112180741-5e0467b6c7ce // indirect
+	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 // indirect
+	google.golang.org/protobuf v1.27.1 // indirect
 )