Merge pull request #24 from ropod-project/develop

• Task temporal information uses TimeStamp objects from ropod_common.
• Add zero timepoint (ztp) with TimeStamp of today midnight. The auctioneer sends the ztp in each task announcement msg. Robots update their ztp based on the received task announcement msg.
• The timetable includes the ztp and a method to convert a task to an stn_task. An stn_task is added to the stn.
• The temporal information in the datasets is the delta time added to datetime.now(), i.e., all tasks are referenced to now when the test starts.
• Dual objective bidding rule: The first objective is the risk metric, the second objective is the temporal metric. Lower risk metrics are preferred, temporal metrics break ties.
• allocation test: clean the ccu_store and the robot_store before starting the test
• Add Auctioneer builder
• Add MRTA builder
• Add TaskLot: references a Task. Includes information needed in the allocation process.
• Use mongo models for TaskLot, Timetable, and performance models
• Remove dependency to ROPOD's fleet_management
• Delete outdated tests