use go1.11 with go mod

vendor/github.com/gin-gonic/gin/fs.go

@@ -1,42 +0,0 @@
-package gin
-
-import (
-	"net/http"
-	"os"
-)
-
-type (
-	onlyfilesFS struct {
-		fs http.FileSystem
-	}
-	neuteredReaddirFile struct {
-		http.File
-	}
-)
-
-// Dir returns a http.Filesystem that can be used by http.FileServer(). It is used interally
-// in router.Static().
-// if listDirectory == true, then it works the same as http.Dir() otherwise it returns
-// a filesystem that prevents http.FileServer() to list the directory files.
-func Dir(root string, listDirectory bool) http.FileSystem {
-	fs := http.Dir(root)
-	if listDirectory {
-		return fs
-	}
-	return &onlyfilesFS{fs}
-}
-
-// Conforms to http.Filesystem
-func (fs onlyfilesFS) Open(name string) (http.File, error) {
-	f, err := fs.fs.Open(name)
-	if err != nil {
-		return nil, err
-	}
-	return neuteredReaddirFile{f}, nil
-}
-
-// Overrides the http.File default implementation
-func (f neuteredReaddirFile) Readdir(count int) ([]os.FileInfo, error) {
-	// this disables directory listing
-	return nil, nil
-}