RS-5211 asset importr - handle 200k row jobs

[stevenjonescgm]

• debugging improvements
• fix some error handling
• DRY resource processors
• reduce processing and memory overhead by iterating the JSON hash without duplicating it
• early quit after 15 errors for quick feedback
• It seems ActiveRecord was scanning import.data on every import.save even when not changed. using update_columns instead for saving job progress saved ~80% of processing time when importing 40,000 assets (in development environment)

[mathmatomancer]

looks good to me, I'm assuming the red in github's view for the bower.json is because it doesn't know what to do with it, not because it's an error?