DM-8182: send email when package successfully completed.

[loitly]

https://jira.lsstcorp.org/browse/DM-8182

• email notification is working properly
• it should also resend email when the email field has changed.

To test:

• goto: firefly/lc.html
• download something.
• when email is given, you should receive email notification when job completes. you should also see 'Email notification sent' in the job status as well.
• bring up background monitor and enter a different email. you should get email notifications for all completed jobs.

[tgoldina]

I got the email when download request was completed, but none of resentEmails worked for me.

(This is the last item in your test sequence. When I enter a different email after the job is completed, I don't receive email.)

Update: the resend does not work only for single file download. For multiple files, things work as stated.

[tgoldina]

Two minor things:

• resend does not work for one file (immediate) download
• no indication in UI that email was resent (if it was sent before)

[loitly]

I've pushed a commit to address the immediate download scenario. Please confirm.

[loitly]

I've pushed a commit to fix the single file scenario not getting email notification. Please confirm.