Merge pull request #287 from qiangdavidliu/2.x

Adding metrics to TaskInvoker in serverRegistry
Fix resource leak in client registration path.
Merge pull request #289 from tbak/2.x

2.x Fix resource leak in client registration path.
Reorganize classes in packages/projects.
Merge remote-tracking branch 'remotes/netflix/2.x' into 2.x
Reorganize classes in packages/projects - cont.
Merge pull request #291 from tbak/2.x

2.x Reorganize classes in packages/projects.
Allow for null values in delta updates.
Merge pull request #293 from tbak/2.x

2.x Allow for null values in delta updates.