Create admin method to clear Fluo table

Method would be helpful for testing and could reside in Core rather than API. The method could wait for a notifications to process and then clear data using Accumulo API.

Start by inspecting the Core and API entry points and the notification-processing path. Determine how an admin method can wait for pending notifications before using the Accumulo API to clear the Fluo table. Done means the method is available in the appropriate layer and supports reliable test cleanup.

Written by the indexing model from the issue text.