let the asset tests run on MySQL. Interesting difference here, the

sqlite driver can handle .Data = Null, the mysql driver can not.  We
should decide which is the right behavior and adjust code for it.

OpenSim/Data/MySQL/MySQLAssetData.cs

@@ -40,7 +40,7 @@ namespace OpenSim.Data.MySQL
     /// <summary>
     /// A MySQL Interface for the Asset Server
     /// </summary>
-    internal class MySQLAssetData : AssetDataBase
+    public class MySQLAssetData : AssetDataBase
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);