Add REST/CLI support for cache topology manipulation

The REST endpoint and the CLI should allow the admin to view and manipulate the topology information:

• get list of cache members
• get topology details: topology id, rebalancing phase, number of segments owned for read/write by each node, number of segments to transfer to each node, maybe in the future number of segments already transferred, number of read/write owners for each segment (maybe the CLI could use histograms to condense the ownership information?)
• get global topology summary: either all the per cache information in a single JSON, or maybe a simplified version that doesn't include or summarizes per-node and per-segment information.
• get/set automatic rebalancing status globally and per cache
• force rebalancing for a cache
• cancel rebalancing for a cache (not yet implemented in core)
• get/set the availability status of a cache