No mechanism for getting a Cluster object from Cluster Manager

Problem/Motivation

When implementing functionality from Elasticsearch Connector programatically, sometimes it is useful to call the default cluster object. Currently in ClusterManager there is a 'getDefaultCluster' function which returns the default cluster ID, and a 'loadAllClusters' function that returns an array of clusters, but usually you only want to get one cluster, such as getting back the default cluster.

Proposed resolution

Need to add a 'loadCluster' function that loads just the requested cluster id.

Remaining tasks

Add code change
Review code change

User interface changes

None

API changes

None

Data model changes

None