fix(response): deal with not found files/packages

Correctly deal with not found files and package by returning the proper
status code.

Fixes #1
Merge branch 'master' of github.com:injoin/blook
docs(readme): match new project name

The project has been renamed to plook, so the readme must use the
same name as well.
chore(travis): configure travis

Added Travis manifest with only Heroku deployment for now.