Toward sustainability: Build an alert system that's triggered when official forms change

[fureigh]

User story:
As a developer, I understand that systems are living and require maintenance. If a county changes the form that they're using, I want to know that as soon as possible so that I can update the tool to serve the appropriate form.

IMPORTANT NOTE: If it turns out from #32 that counties will accept older forms even after they update theirs, this may prove unnecessary (or, at least, lower priority).

Current behavior:
I only know that a county has changed their form if someone's personal contact (at that county, doing legal assistance, etc.) notices and thinks to inform me.

Desired behavior:
When the online version of one of these forms changes, I receive a notification so I can investigate whether and how the tool needs to be updated.

“Something's different about COUNTY's form. Take a look: NEW_URL" (Exact text TBD.)

Technical notes:

• The tool works with archived local versions of PDFs. This is about detecting changes in the online versions.
• Scraper/Selenium tests.
• Don't get wrapped up trying to have the tool intelligently discern the nature of the changes. Just flag that something has changed and notify a human.
• Check for changes in filename.
• Also check for last-updated timestamp.
• Consider checking for changes in content of any related official page explaining the process
• Simplest version: Email, presumably, or a text.
• Enhanced dream version: Use GitHub hooks to automatically create issues in this queue.