Provide uniform Clustering Services across AD-SAL and MD-SAL

In the current version of the controller we do support data clustering using Infinispan. Infinispan is a key value store that provides notifications on data changes. This form of clustering is primarily being used by AD-SAL applications. One drawback of Infinispan is that it only supports storing data in a Map structure which is not very efficient when it comes to storing trees. The MD-SAL provides a datastore which stores all the data in a hierarchical tree like structure which closely models the yang model defined by a service provider.

We need a solution which does the following,

1. Allow clustering of data regardless of the data structure. At the very mininmum we need to support both a key-value type of store and a tree store.
2. Use the same clustering and remoting mechanism for invoking remote operations and for notifications.

This needs to be fixed in Helium