Add opt to disable print logs but storing to file

By default outputs contains "stdout", which prints the logs at the
output of the process. To add a log file as output, the path should be
added at the outputs array. To avoid printing the logs but storing them
on a file, can use []string{"pathtofile.log"}

log/log_test.go

@@ -5,7 +5,7 @@ import (
 )
 
 func TestLog(t *testing.T) {
-	// Init("debug", "test.log")
+	// Init("error", []string{"stdout", "test.log"})
 
 	Info("Test log.Info", " value is ", 10)
 	Infof("Test log.Infof %d", 10)