fix start.sh in crontab run failed problem

start.sh

@@ -1,10 +1,15 @@
-#!/bin/bash -
-#
+#!/bin/sh -
 # Copyright 2014 The Gogs Authors. All rights reserved.
 # Use of this source code is governed by a MIT-style
 # license that can be found in the LICENSE file.
 #
 # start gogs web
 #
-cd "$(dirname $0)"
-./gogs web
+IFS=' 
+	'
+PATH=/bin:/usr/bin:/usr/local/bin
+HOME=${HOME:?"need \$HOME variable"}
+USER=$(whoami)
+export USER HOME PATH
+
+cd "$(dirname $0)" && exec ./gogs web