Load data job events

Change the socket events to be sent in the ``load_job_data`` function, rather than in the ``log_parser``.  This means we now send socket.io job events for pending and running jobs as well as complete.

* remove sending socket events in the log parser
* add sending socket events in ``load_job_data``
* add a function called ``_remove_existing_jobs`` which is called at the beginning of ``load_job_data`` to remove any jobs we already have in the db with the same state.
* remove publishing error events because we don't use them anymore.  we use the ``unclassified failures`` instead.