Refactor Chord.js
Modify RequestHandler.js to handle errors.
Refactor to use isZeroOrPositiveNumber or isPositiveNumber.
Add log.
Add debug log.
Modify to return if errored in tasks.
Add maximum retry count to notify-and-copy in #join.
Fix test.
Add test cases to IDSpec.js.
Update join process.
Changed FingerTable._remoteNodes from object to list
Add get/setEntries API to Chord class
Fix bug
Merge upstream and resolve conflicts