Fix FutureWarning in plotting by deregistering matplotlib converters (the future behavior). Also fix bad date formatting in non-daily plot that started came with change in matplotlib default in 3.0.2
Fix FutureWarning in plotting by deregistering matplotlib converters (the future behavior). Also fix bad date formatting in non-daily plot that started came with change in matplotlib default in 3.0.2

facebook/prophet,facebookincubator/prophet,facebook/prophet,facebookincubator/prophet,facebook/prophet