Create Fluo developer tool

While the monitoring tool (see #20) is geared for admins to track the health of a Fluo cluster, a tool is needed for developers to help them debug observers. While they have separate use cases, the developer & monitoring tool could be merged into one.

Below are some possible features for Fluo developer tool:
1. Have worker store last 50 log messages (any level) and last 50 error messages for observers and have tool retrieve them.
2. Retrieve statistics for individual observers.

Start by reading issue #20 and locating the existing worker and monitoring-tool entry points. Define the scope with maintainers before implementation; done would include an agreed developer tool that retrieves observer logs, errors, and individual observer statistics.

Written by the indexing model from the issue text.