Add support for generic "peer" based scaling in/out and load balancing APIs.

1. The actual scaling actions will be implemented independent of the application (or framework/state managers).
2. The decision making should be left to the framework implementer (e.g. cw's graph framework). Need a clean API for this. 
   -- might need information about various system and application level metrics.
   -- might need information about the neighbor as well.
