Features: add title filtering and hourly slicing when date range is specified

[erikpaasonen]

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Description

Improvements to the mass_update_incidents script:

• date_range parameter now supports windows which include more than 10K incidents by batching up into 1-hour time slices and running against those
• Added support for filtering incidents by Title, so as not to accidentally close other incidents unrelated to the bulk incident activity

Implementation

I'm unsure what is being asked for here.

Steps to test changes

• Generate 30K incidents or so
• Run mass_update_incidents.py with the --date-range paramter and give it the range covering all incidents
• Watch it retrieve batches of incidents and handle as before

Documentation

• There is documentation that needs to be updated upon merging these changes

Note: Modified README.md with the new behavior.

Links to any documentation to be updated: