Add a very small test for the CLI

This adds a super small test suite for the CLI. Essentially to verify my
fix for #373 but we can build upon it later to test more stuff.

Part of #373
Activate new test suite in Travis-CI config

Part of #373.
Rename order to order_id

This was missed when we renamed order - we simply forgot to update the
CLI! Thanks to dosomder for pointing this out!

Fixes #373.