Adding different async workflow examples for HN

- Callback Hell Scraper
- Promised Scraper
- Async workflow using async.series / async.parallel and Q.all
Add task 3 for week6
Add task 4 for week6
Add notes for creating a fake video device
Add chat task for week7
Add text UI modules in week 7 chat assignment
Add slides for week8
Add final task
Fix week8 folder structure
added solutions