add session middleware (#174)

README.md

@@ -42,3 +42,4 @@ Each author is responsible of maintaining his own code, although if you submit a
 + [gin-access-limit](https://github.com/bu/gin-access-limit) - An access-control middleware by specifying allowed source CIDR notations.
 + [gin-stats](https://github.com/semihalev/gin-stats) - Lightweight and useful request metrics middleware
 + [gin-health-check](https://github.com/RaMin0/gin-health-check) - A health check middleware for Gin
++ [gin-session-middleware](https://github.com/go-session/gin-session) - A efficient, safely and easy-to-use session library for Go.