Upgrade gin-gonic to latest master, fix compatibility issues

vendor/github.com/gin-gonic/gin/ginS/README.md

@@ -0,0 +1,17 @@
+# Gin Default Server
+
+This is API experiment for Gin.
+
+```go
+package main
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/gin-gonic/gin/ginS"
+)
+
+func main() {
+	ginS.GET("/", func(c *gin.Context) { c.String(200, "Hello World") })
+	ginS.Run()
+}
+```