在 Quick Server 安装目录外执行 stop_quick_server.sh/start_quick_server.sh 等脚本时，无法读取 conf/config.lua 文件

错误信息：

```
/opt/quick_server/bin/openresty/luajit/bin/lua: (command line):1: module 'conf.config' not found:
no field package.preload['conf.config']
no file './conf/config.lua'
no file '/opt/quick_server/bin/openresty/luajit/share/luajit-2.1.0-alpha/conf/config.lua'
no file '/usr/local/share/lua/5.1/conf/config.lua'
no file '/usr/local/share/lua/5.1/conf/config/init.lua'
no file '/opt/quick_server/bin/openresty/luajit/share/lua/5.1/conf/config.lua'
no file '/opt/quick_server/bin/openresty/luajit/share/lua/5.1/conf/config/init.lua'
no file './conf/config.so'
no file '/usr/local/lib/lua/5.1/conf/config.so'
no file '/opt/quick_server/bin/openresty/luajit/lib/lua/5.1/conf/config.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
no file './conf.so'
no file '/usr/local/lib/lua/5.1/conf.so'
no file '/opt/quick_server/bin/openresty/luajit/lib/lua/5.1/conf.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
[C]: in function 'require'
(command line):1: in main chunk
[C]: at 0x004049d0
```