Add option to include author name in body of notification email

See the discussion on https://github.com/gitlabhq/gitlabhq/commit/ddd806c66f7b1b064243f81e36412ddbe557b8da (cc @huacnlee).

Some Exchange configurations don't allow applications like GitLab to override the sender on outbound email, which means the issue/MR/note author will not be anywhere in the notification email.

303f79f8 added "X wrote:" to every notification email, but this looked odd when the author name was already in the sender field.

I think we should make this configurable, as a fallback for those systems that can't use the sender to show the author.

cc @JobV

Is there a way we can detect these configurations and do it automatically, skipping the option?

@rspeicher Not that I know of, we can't know if the SMPT server is Exchange and/or if this setting is enabled. We already have email_from/email_reply_to/email_display_name, I think we can add another option.

mentioned in merge request !2495 (closed)

mentioned in commit 9474e36f

mentioned in merge request !2767 (merged)

Status changed to closed by merge request !2767 (merged)

mentioned in commit 706b101f