Update SerilogLogger.cs

Fixed #34

Author: scott-xu

src/Ninject.Extensions.Logging.Serilog/Infrastructure/SerilogLogger.cs

@@ -338,7 +338,7 @@ public override void InfoException(string message, Exception exception)
         {
             if (this.IsInfoEnabled)
             {
-                this.serilogLogger.Fatal(exception, message);
+                this.serilogLogger.Information(exception, message);
             }
         }
 
@@ -415,7 +415,7 @@ public override void Warn(string format, params object[] args)
         {
             if (this.IsWarnEnabled)
             {
-                this.serilogLogger.Fatal(format, args);
+                this.serilogLogger.Warning(format, args);
             }
         }
 
@@ -429,8 +429,8 @@ public override void Warn(Exception exception, string format, params object[] ar
         {
             if (this.IsWarnEnabled)
             {
-                this.serilogLogger.Fatal(exception, format, args);
+                this.serilogLogger.Warning(exception, format, args);
             }
         }
     }
-}
+}