Import an existing Database dump from an existing choko app

[sebas5384]

When we work with a team of developers, we need a way to import and export dumps, to start an existing project.

Something like:

cd ./apps/project-name
choko db import exports/db.json

[recidive]

Cool, I believe we can use mongodump for exporting and the cli for importing.

This depends on #106.