[fix bug 945831] Task to send digest of report activity to mentors.
[fix bug 966987] Display mentor in reports.
Merge pull request #614 from glogiotatidis/966987

[fix bug 966987] Display mentor in reports.
Merge pull request #612 from glogiotatidis/945831

[fix bug 945831] Task to send digest of report activity to mentors.
[fix bug 966977] Send an email when a user adds a comment on a NGReport.