Rebuilt around mfetcher instead of capsule.

mfetcher is just capsule hacked up to provide better feedback in success and
failure cases. This removes the need to reverse engineer Maven artifact
coordinates from ~/.m2 paths, and more importantly, it greatly improves
behavior when Maven artifacts cannot be resolved and/or downloaded.

We can now mark those dependencies as missing instead of having the entire
dependency resolution process blow up in our face and render everything
unusable.

This also includes a Log revamp which makes this work more properly when Scaled
reroutes logging to the *messages* buffer.