Sample batches for auto MTurking using Rails, not Python

[utanashati]

For this, we would have to use a more advanced scheduler that allows running a rake task each few months (AWS cron is now set up to run on the 1st of every month).

On the Rails side, there should be

• A new PipelineApi function in place of check_samples_status that would do the Elasticsearch sampling directly.
• A new rake task in place of check_samples_status that would do the same thing but take output of the new function.