- The inviter name is added to the devise file app/views/devise/mailer/invitation_instructions.html.erb
- The name of person invited the plan is shared with is added to the greeting if it exists for both the devise
and non-devise emails (repectively app/views/devise/mailer/invitation_instructions.html.erb and app/views/user_mailer/sharing_notification.html.erb).
Otherwise, the invited person's email is displayed in the greetings.

Fix for #1931