Minor: change the return value of unsuccessful posts to string.Empty.

OpenSim/Region/CoreModules/Framework/InventoryAccess/HGAssetMapper.cs

@@ -113,7 +113,7 @@ namespace OpenSim.Region.CoreModules.Framework.InventoryAccess
                         asset1.Data = asset.Data;
 
                     string id = m_scene.AssetService.Store(asset1);
-                    if (id == UUID.Zero.ToString())
+                    if (id == string.Empty)
                     {
                         m_log.DebugFormat("[HG ASSET MAPPER]: Asset server {0} did not accept {1}", url, asset.ID);
                         success = false;

OpenSim/Services/HypergridService/HGAssetService.cs

@@ -137,7 +137,7 @@ namespace OpenSim.Services.HypergridService
         public override string Store(AssetBase asset)
         {
             if (!m_AssetPerms.AllowedImport(asset.Type))
-                return UUID.Zero.ToString();
+                return string.Empty;
 
             return base.Store(asset);
         }