Fast construction of BaseStoreRoutingPlan objects

Cleaned up code that was quickly hacked to ensure BaseStoreRoutingPlan
objects are "fast" to construct. In this clean up, managed to make
construction constant time (sub-microsecond on my
workstation). Basically, the struct that had been expensive to construct
already existed in the Cluster object and its reference could simply be
copied.

Cluster.java
- renamed "numberOfTags" to "numberOfPartitionIds"
- replaced map with array for partitoinIdToNode lookups

BaseStoreRoutingPlan
- TODOs and comments

ConsistentRoutingStrategy
- simply copy the partitionIdToNode lookup from cluster object

StoreRoutingPlan
- Pre-compute the mapping of partition Id to replicating list
- TODOs and comments

test/integration/voldemort/performance/StoreRoutingPlanPerf.java
- performance test of various cluster/storedef combos:
  - BaseStoreRoutingPlan (fast to construct!)
  - StoreRoutingPlan (slow to construct, but faster than it had been)
  - PartitionBalance (slow to construct, but faster than it had been)
Address minor code review feedback

- cleaned up TODOs and comments
- added TODO to incorporate Abhinays work on "metadata listener"
Added pending release notes.
Avoid potential null pointer deref of config
Change Repartioner to swap among nodes from all specified zones.

PartitionBalance
- Added comment about possible weakness of our utility method.

Repartitoiner.java
- Changed random shuffle implementation to swap among all nodes in
  specified zones.
- Left TODOs and 'dead code' implemntation of intra-zone swapping vs
  inter-zone swapping.
Add rebalance shuffle script
Fix location of example stores
Add cluster expansion script
Fix comments
Get rid of tee-ing the plan to a separate file

The rebalance planner writes the output to a file named
plan.out so this is not needed anymore.
Remove vold_home parameter from scripts

These scripts are being shipped as part of vold repo and so
no need for this extra parameter.
Copy plan outout to the final directory
Cleanup minor typos and comments
Expose max contiguous partitons option to script
Make repartitioner interface consistent + cleanup
More cleanup to repartitioner

Fix varible names, typos add comments
Rename new cluster script
Copy analysis file to output_dir
Preparing release 1.4.4 with rebalancing improvements
Fix NPE in the test code

Pass an empty list instead of a null.