New backend for Citrix Sharefile - Fixes #1543

Many thanks to Bob Droog for organizing a test account and extensive
testing.

backend/sharefile/generate_tzdata.go

@@ -0,0 +1,22 @@
+// +build ignore
+
+package main
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/shurcooL/vfsgen"
+)
+
+func main() {
+	var AssetDir http.FileSystem = http.Dir("./tzdata")
+	err := vfsgen.Generate(AssetDir, vfsgen.Options{
+		PackageName:  "sharefile",
+		BuildTags:    "!dev",
+		VariableName: "tzdata",
+	})
+	if err != nil {
+		log.Fatalln(err)
+	}
+}