Add optional syslog logrus hook (#343)

* add optional syslog logrus hook

* document syslog

vendor/gopkg.in/mcuadros/go-syslog.v2/handler.go

@@ -0,0 +1,35 @@
+package syslog
+
+import (
+	"gopkg.in/mcuadros/go-syslog.v2/format"
+)
+
+//The handler receive every syslog entry at Handle method
+type Handler interface {
+	Handle(format.LogParts, int64, error)
+}
+
+type LogPartsChannel chan format.LogParts
+
+//The ChannelHandler will send all the syslog entries into the given channel
+type ChannelHandler struct {
+	channel LogPartsChannel
+}
+
+//NewChannelHandler returns a new ChannelHandler
+func NewChannelHandler(channel LogPartsChannel) *ChannelHandler {
+	handler := new(ChannelHandler)
+	handler.SetChannel(channel)
+
+	return handler
+}
+
+//The channel to be used
+func (h *ChannelHandler) SetChannel(channel LogPartsChannel) {
+	h.channel = channel
+}
+
+//Syslog entry receiver
+func (h *ChannelHandler) Handle(logParts format.LogParts, messageLength int64, err error) {
+	h.channel <- logParts
+}