Change the subject format for comment notifications

Is your feature request related to a problem? Please describe

This is just a very small problem, but with an easy solution ;) Right now the format of the subject of new comment notification emails is: "There is a new comment by XXXX in YYYY"

This causes that each new comment by a different person in the same proposal generates a new thread. Many email clients group mails by thread if they share the subject, and it would make sense that all notification emails from the same proposal form a unique thread, and not many.

Describe the solution you'd like

Change the subject of these mails to: "New comment in YYYY"

Does this issue could impact on users private data?

No.

Funded by

Populate (actually it's a very small change, just to mean that we could do it)