Split RouteAggregatorService into Aggregator and CostTable services

[derekkingston]

Rather than have two different, distinct roles, the RouteAggregator service should only work to create and respond to large, heterogeneous route plan requests. The additional functionality of computing the task-to-task route-cost table should be separated out into a stand-alone service for overall system simplicity and reduction of complexity in the RouteAggregator.