Add progress bar and/or message on current task

[mehmetaergun]

Summary

It would be nice if it provided some kind of interface that shows more or less exactly what it is doing at a given time when running checks.

Steps to reproduce

1. Run checks on large dataset
2. Cannot tell if it's still working on tasks, what it is doing, and whether it crashed or not.

Expected behavior

Provide some information as to what is happening and an indication as to whether it crashed due to memory issues etc.

Relevant logs and/or screenshots

• debian 8, 4GB RAM (virtual machine)
• dataset: US population estimates at http://www.census.gov/popest/data/cities/totals/2015/SUB-EST2015.html ("All States", http://www.census.gov/popest/data/cities/totals/2015/files/SUB-EST2015_ALL.csv)

Thanks :)