Un-mute logging in debug mode

[danpat]

We're suppressing debug messages from osrm-backend. We should stop that, debug messages are useful, especially if you explicitly ask for a debug build.

[daniel-j-h]

@danpat what was your idea here? To have debug messages coming from libosrm through the Node.js bindings printing messages to stdout? Please clarify, close here and move to the backend.