Include dest path for published files in the notification emails

[mhidas]

I've already mentioned this in #48, but it's been specifically requested by a data provider, so I'll create a separate issue for it. For files that get successfully published, we should include details of where they got published to in the notification email.

[mhidas]

Possible solutions:

• Include dest path in each row of the "File collection details" table;
• Add a separate table, or a simple list, of dest paths at the bottom of the email;
• Add a list of URLs as an attachment.

If the dest paths are included in the email, they could also be made into direct S3 download links (or even OPENDAP links, for nc files).