Feature - Pass image parameters to InstallService

[cwegener]

Description: Make InstallService a variadic function to allow passing of image parameters through to (*Mgr).CreateService

Example snippet:

params := []string{"-config", "C:\\my.conf"}
err := winsvc.InstallService("C:\\svc.exe", "SvcName", "Svc Desc", params...)

Since InstallService has been turned into a variadic function, the following call to InstallService still works fine:

err := winsvc.InstallService("C:\\svc.exe", "SvcName", "Svc Desc")

[chai2010]

thanks