Enables script access to the per object dynamic attributes through the JsonStore

script functions. Adds JsonAttachObjectStore to associate a store identifier with
an object (scripts can only access the store in their host object, this could be
extended but isn't necessary for now).

Note this opens a method to the DAMap OSDMap. This will be removed later, but
greatly simplifies the code for now.

The JsonStore and these scripts are disabled by default.

OpenSim/Region/Framework/Interfaces/IJsonStoreModule.cs

@@ -35,6 +35,7 @@ namespace OpenSim.Region.Framework.Interfaces
 
     public interface IJsonStoreModule
     {
+        bool AttachObjectStore(UUID objectID);
         bool CreateStore(string value, ref UUID result);
         bool DestroyStore(UUID storeID);
         bool TestStore(UUID storeID);