Do something about figures.models.PipelineError

[johnbaldwin]

Figures pipeline error logging to figures.models.PipelineError needs some TLC and decisions

• Do we keep it or remove it and default to platform loging (which goes to the log files)?
• If we keep it, we need to make it more useful. At the least make a convenience management command to prune DB rows, perhaps add to the daily job to remove records "older than X" for example.
• Maybe we make it a plugin to Figures