Flush the log on interrupt and shutdown events

[jimmyrcom]

For example if the server is shutting down or the user clicks Ctrl+C on a console application, the log will flush any pending messages.

This can be tested file_logger_test.go with the following lines. Execute then click ctrl+c

logger, err := toolbox.NewFileLogger(toolbox.FileLoggerConfig{
    LogType:           "test",
    FileTemplate:      "/tmp/interrupt.log",
    QueueFlashCount:   500000,
    MaxQueueSize:      100000,
    FlushRequencyInMs: 120000,
    MaxIddleTimeInSec: 100000,
})

assert.NotNil(t, err)

logger.Log(&toolbox.LogMessage{
    MessageType: "test",
    Message:     fmt.Sprintf("Hello"),
})
time.Sleep(400 * time.Millisecond)
logger.Log(&toolbox.LogMessage{
    MessageType: "test",
    Message:     fmt.Sprintf("World"),
})

time.Sleep(1000 * time.Second)

Because the test is a terminate process test, I don't see how we could add it to the test suite.