[longomatch] Don't serialize RateString

[Andoni Morales Alastruey <amorales src gnome org>]

commit d3c3f8fa736f73312b1fe8f449afb4e139f0d2aa
Author: Andoni Morales Alastruey <ylatuya gmail com>
Date:   Mon Mar 2 17:53:17 2015 +0100

    Don't serialize RateString

 LongoMatch.Core/Store/TimeNode.cs |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/LongoMatch.Core/Store/TimeNode.cs b/LongoMatch.Core/Store/TimeNode.cs
index 70ecd6b..25dcb7d 100644
--- a/LongoMatch.Core/Store/TimeNode.cs
+++ b/LongoMatch.Core/Store/TimeNode.cs
@@ -110,6 +110,7 @@ namespace LongoMatch.Core.Store
                        set;
                }
 
+               [JsonIgnore]
                public string RateString {
                        get {
                                return String.Format ("{0}X", Rate);