Fix JSF Email document notification to mail all members of a group

WHAT: With a structure of groups such as group gA with members mA and (group g1 with members m1 and (group g2 with member m2)), there should be mails sent to mA, m1 and m2. In fact, only mA and m1 are mailed.

How to reproduce

• boot a fake SMTP receiver and target it
• Boot a 10.10 instance with JSF
• create a group g2 with user m2 as member
• create a group g1 with user m1 as member and group g2 as subgroup
• create a group gA with user mA as member and group g1 as subgroup
• create a Folder "Folder"
• create a Note-typed document in "Folder"
• in "Folder", hover over the Note-typed document, right clck and select "Email" in the contextual menu
• Fill in the mail targeting group "gA"
• see that mail are only sent to mA and m1, and that m2 is forgotten

Expected result
m2 is part of GA, and should also be mailed, in addition to mA and m1.