add ParseLevel to get Level from string

logrus.go

@@ -1,6 +1,7 @@
 package logrus
 
 import (
+	"fmt"
 	"log"
 )
 
@@ -30,6 +31,27 @@ func (level Level) String() string {
 	return "unknown"
 }
 
+func ParseLevel(lvl string) (Level, error) {
+	switch lvl {
+	case "panic":
+		return PanicLevel, nil
+	case "fatal":
+		return FatalLevel, nil
+	case "error":
+		return ErrorLevel, nil
+	case "warn", "warning":
+		return WarnLevel, nil
+	case "info":
+		return InfoLevel, nil
+	case "debug", "dbg":
+		return DebugLevel, nil
+	}
+
+	var l Level
+	return l, fmt.Errorf("not a valid logrus Level: %q", lvl)
+
+}
+
 // These are the different logging levels. You can set the logging level to log
 // on your instance of logger, obtained with `logrus.New()`.
 const (