Remove unused parts of LinkedIn API

Fix whitelist logic to handle empty lists.
Update copy for LinkedIn e-mail.
Migrations for LinkedIn.

Clean up common.

Add the ability to dry-run the command without sending e-mail.

Don't save courses sent during a dry run

Switch to EmailMessage for LinkedIn so we can send HTML emails

Update subject copy.

Use correct name for CertificationName

Fix up certificate url information.
Use S3 uploaded image for e-mail button.

Add in a tracking pixel.

Add in alt text for profile image
Add email send error checking.

Add manual transaction handling.

Remove grandfather option
Add in test to test the transactions when we hit an unexpected error.

Add tests for various error mail sending scenarios
Minor data collection tweaks after examining prod course data.

Add in unicode handling for names.