DataFederation : Definition of persistence and retrieval of objects from federated datastores

[andyjefferson]

Once the user has defined which datastores are federated for this PMF/EMF and which classes/objects are persisted into which datastore, then we need to produce the logic for handing off persistence and retrieval to the correct StoreManager.

We need to update QueryManager to allow for federation. The StoreManager needs to returns the Query object (instead of QueryManager currently), so then FederatedStoreManager can pass a query object that will handle the federation of query results.

Also need to take into account that the secondary datastore name is lowercased during the persistence property read, so need to do case-insensitive search for datastore name

Similarly need to update wrapper classes to get hold of the actual StoreManager for the object, maybe via a method on ObjectProvider which goes via ExecutionContext and if we have FederatedStoreManager then gets the right one - this is now done.