Problem: Emails are being sent to all email addresses/everyone who made in a
change. But some developers might only be interested in notifications when
"trunk/logging/*" is among the list of modified files.

This setting allows to specify patterns (*, ?) for which the modified file paths
and names are matched against (also see <email>/<fileRegExpr>
http://cruisecontrol.sourceforge.net/main/configxml.html#email), and only when
one of the pattern matches an email is being sent.

It probably makes sense to allow for use of regular expressions, too, but
because of their relative complexity, because they tend to be hard to read and
maintain, in comparison to patterns, i'd prefer the latter.

I imagine the user interface to look like this:

Email Address [myemail@mycompany.com ]
File name filter [/trunk/logging/* ]
File name filter [/trunk/reporting/jsps/*.jsp ]

(Add more file name filters...)
(Add more Email addresses...)