Take over GoTTY maintainership

@yudai built this amazing piece of software, but it now needs a new,
active maintainer. I'm taking a stab at it.

backend/localcommand/factory.go

@@ -4,7 +4,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/yudai/gotty/server"
+	"github.com/sorenisanerd/gotty/server"
 )
 
 type Options struct {