Merge pull request #105 from phemmer/entry_warning

Add missing `(*Entry) Warning()` function

entry.go

diff --git a/entry.go b/entry.go
index e164eec..17fe6f7 100644
--- a/entry.go
+++ b/entry.go
@@ -126,6 +126,10 @@
 	}
 }
 
+func (entry *Entry) Warning(args ...interface{}) {
+	entry.Warn(args...)
+}
+
 func (entry *Entry) Error(args ...interface{}) {
 	if entry.Logger.Level >= ErrorLevel {
 		entry.log(ErrorLevel, fmt.Sprint(args...))