bugfix/mongo_2.6.5_project fix bad getNext code:
1. error callback had arguments in wrong order
2. spurious return statement returned bad stuff
3. code cleanup
Update ProjectDocumentSource.js

Fixed. There's no reason to bloat the closure.
Merge pull request #145 from RiveraGroup/bugfix/mongo_2.6.5_project

fix bad ProjectDocumentSource.getNext() code