RFE: Provide method for sending commit comments to an email list (BB-15974)

At present, it is possible to have email sent to an email address, which may in turn be a mailing list. This provides a method for team members and interested parties to follow commits. However, if a team member adds a comment to a commit. I haven't confirmed this, but it may also be that someone watching the commit will receive notice of the comment and/or someone watching the repo. may also see this comment. Watching a specific commit is an unlikely action, and watching an entire repo. is both overkill in our case (because we have a mailing list set up) and notices won't be seen by team members who happen not to have a bitbucket user-id.

Suggestion: provide a method for either having commit comments sent to the mailing list associated with commits and/or a separate mailing list for tracking comments on commits only.