add switch of new fileMode inherit org fileMode and the config of fileMode

[guoshengfei]

Make fileMode configuration more flexible, and two config：

type Logger struct{
// Opening the new log file mode, 0600 is the default.
FileMode os.FileMode json:"filemode" yaml:"filemode"
// New file whether inherit orginal mode, false is the default.
InheritOrgFMSwitch InheritSwitch json:"inheritswitch" yaml:"inheritswitch"
}