Add tests to cover the InfoMander class

[thomass-dev]

No description provided.

[thomass-dev]

I noticed some issues that might be worth discussing:

• it seems that the prefixed template directory wasn't used (fixed)
• artifacts were stored on both cache and disk (fixed)
• i change the updated_at field from time to datetime
• logs are stored in the cache, not on disk as mentioned
• in the add_info method, in append mode, new values are putted in front of the list
• the method dsl_path_exists is not used anywhere and is based on assert

[tuscland]

LGTM

[thomass-dev]

As discussed with @rouk1, to resolve conflicts between #34 and #36 , we will change the way the dashboard is launched and discover mandr.

At this state, we only want to launch a dashboard on an instance of mandr and all its children.
So, we'll create a launch_dashboard method inside the mandr class, so that we can easily retrieve infos and children without worrying about passing the store path from the URL to the backend dashboard.