Merge changes I66335247,I24ebd4b1,If2470ac2,Ia36e2a7c,If7549425, ...

* changes:
  Make sure QNameFactory cache is constant
  Use a singleton instance for DefaultShardStrategy
  Speedup ModuleShardStrategy a bit
  Optimize getAllShardNames()
  Optimize getShardNamesFromModuleName()
  Optimize getModuleNameToShardStrategyMap()
  Optimize getModuleNameFromNameSpace