notebook updates

[reubano]

Didn't want to submit a PR just yet. My changes may a bit too radical for your tastes :). So here's a breakdown of what I've done:

1. lowercased 'riko'
2. updated to Python 3
3. put working dir into a const (CWD)
4. replaced str concatenation with path.join
5. formatted raw html strings
6. used try/except blocks instead of dir checking
7. replaced inline output with notebook output
8. moved comments above code to reduce line width (for viewing on smallish screens)
9. replaced itertools.islice with the truncate pipe
10. replaced synchronous iterator with dotdict attribute fetching
11. replaced type checking with duck typing
12. nicely formatted articles (last example)

let me know your thoughts

[reubano]

10 should be made unnecessary with nerevu/riko#20
11 should be made unnecessary with nerevu/riko#22

[aemreunal]

Thank you for all the work you've done and sorry that it took me a lot of time to write a reply. Graduate school at CMU takes a lot of time :)

I would've chosen Python v3 but the course required v2. I suppose a lot of great improvements could be done on the tutorial; hopefully it will be great start for whoever is interested in using it. I have not been through this list but I can get back to this after graduation at the end of December.

Thank you very much!