System.Management 命名空间
http://msdn.microsoft.com/ZH-CN/library/gg145024(v=vs.110).aspx
ManagementObjectSearcher Class
http://msdn.microsoft.com/en-US/library/system.management.managementobjectsearcher.aspx
Win32_PrintJob class
http://msdn.microsoft.com/en-us/library/aa394370.aspx
Win32_Printer class
http://msdn.microsoft.com/zh-cn/library/aa394363.aspx
http://code.msdn.microsoft.com/CCS-LABS-WMI-Getting-13c9cc6a