Dev update emails

Updated all of the emails stored in /orcid-core/src/main/resources/org/orcid/core/template/. As part of this update, in addition to general email text update:

* created a README file describing each of the emails and what they are used for
* added a verification reminder email (verification_reminder_email.ftl) that I hope we can send 1 week after the primary email address is set if the account is still active and the primary email address has not be verified. Added a sendVerificationReminderEmail() function in NotificationManagerImpl.java, but no trigger to send out this email.
* Clarified that the verification_email_w_crossref.ftl is the placeholder for a semi-annual push that will be sent out similarly to the way that we did on Jun 12/13.
* Added updates and suggestions to the sendNotificationToAddedDelegate() function in NotificationManagerImpl.java. I know that this email is not being used yet, though made suggestions for its future release including using the ORCID iD holder's email address as the From address.

Quick note on the updates - the api_record_creation_email.ftl and claim_reminder_email.ftl are still under review by university members, so they may change again. I can change them in the parameter version if that is easiest.

As part of this update I ALSO updated the related [Google Doc internal specification for emails](https://docs.google.com/a/orcid.org/document/d/1eK7mNZCPAtcUTeB-JKCBNW956KdWtw0SlI4jYN5-DUY/edit?usp=sharing)

Final note - The changes I made need a good review. I am not yet able to do local testing. While I've double checked everything that I did, there currently is no way for me to know for sure. I'll get all set up there next week.