2.7.0 (2019-03-05)

• Make event handlers configurable: this allows for e.g. adding your own notifier for specific events
• Switch slack to use events for notifications of interactive pipeline runs
• Fix an edge case bug where reverting a commit after an error in the table creation for an incremental load
  job would not recreate the original tables leading to a failed load
• Fix an edge case bug where crashing during a triggered (code change, TRUNCATE) full load of an
  incremental load job after the table was already loaded would not rerun the full load
  leading to missing data
• Optimize how we set the spawning method in multiprocessing