Issue 413: Encrypt sensitive data in the event table

[mercedesb]

I rule and have completed some work on Case Manager that's ready for review!

This PR encrypts sensitive event data at-rest.

This pull request makes the following changes:

• Encrypts sensitive event columns
• Adds post-deploy rake task to encrypt existing event data
  • run rails event:encrypt_sensitive_columns after you deploy this branch
  • if you run a select query on the events table in production, you should see both cm_name and patient_name are encrypted
• Removes note encryption task that has already been run in production (this is just some clean up)

(If there are changes to the views, please include a screenshot so we know what to look for!)

It relates to the following issue #s:

• Bumps Use attr_encrypted or symmetric_encryption for protecting sensitive data at rest? #413

For reviewer:

• Adjust the title to explain what it does for the notification email to the listserv.
• Tag this PR:
  • feature if it contains a feature, fix, or similar. This is anything that contains a user-facing fix in some way, such as frontend changes, alterations to backend behavior, or bug fixes.
  • dependencies if it contains library upgrades or similar. This is anything that upgrades any dependency, such as a Gemfile update or npm package upgrade.
• If it contains neither, no need to tag this PR.

[mercedesb]

Encrypting number fields would require some non-trivial custom logic, so we've updated the requirements to encrypt the sensitive string fields on the Event model

[colinxfleming]

marvelously clean and works great! thank you much @mercedesb and sorry for the delay in getting this reviewed and in.