set CommandTimeout = 0 in the migration commands so that long

migrations (like converting asset ids) don't run into the 
normal 30 second kill switch.

OpenSim/Data/Migration.cs

@@ -134,6 +134,8 @@ namespace OpenSim.Data
             {
                 int newversion = kvp.Key;
                 cmd.CommandText = kvp.Value;
+                // we need to up the command timeout to infinite as we might be doing long migrations.
+                cmd.CommandTimeout = 0;
                 cmd.ExecuteNonQuery();
                 
                 if (version == 0)