Generate emails from eligible voters in voters.yaml

[geekygirldawn]

Created a script that takes an Elekto voters.yaml file and a GitHub org name as input to generate a list of emails for registered voters. I'm contributing it to Elekto as suggested by @jberkus.

A few notes and things you might want me to change:

• I created a scripts directory for this in what seemed like a logical place (to me), but let me know if you want me to move it.
• Right now, I'm reading in the GitHub personal access token as keyboard input, which is less than ideal, but easy. I'm happy to change this if you let me know your preferred method. We should keep in mind that the person running the script is likely an election officer, and not necessarily the person running the Elekto instance, and they are probably running it locally, rather than on the server where Elekto is running, which probably impacts how we want to get the key.

[jberkus]

I think this is good enough as an example script. If folks want to add refinements, they can do that as additional PRs.