fix(server): avoid error when the file is not found in GitHub
docs(readme): add usage info
chore(release): release v0.1.1
fix(server): send charset in Content-Type

When GitHub sends a charset (it's always UTF-8), we'll do that too.

Fixes #12
chore(release): release v0.1.2
feat(api): create Plook class and a utility toolbelt

In a first try to create an API for standardized package discovery
inside Plook, a Plook class has been created with a utility toolbelt.