Updated documentation for getting started, deployment and dep. mgmt.

Updated Heroku deployment docs since it was out of date. 

Also changed app/index.html location properly since it has been moved from public/index.html to app/index.html.

Finally, added couple of rows for managing dependencies. I wasn't really sure what to put there since linking to their official would be more DRY. Maybe an example how to add bootstrap/foundation?

Wish I knew more about EAK so that I could fill in all the blanks in the docs.