Implement differential privacy in Group Statistics page

Hi Professor,

I'm uploading patch for Deliverable 3. While doing some testing, I found a bug from previous Deliverable 2. I missed to display decrypted group item_name in the Statistics page. So it was showing the encrypted names under Thread. I fixed it in this commit.

There's another issue I found in latest master. When further testing by cloning the current work, like you suggested, I found that there's no private_default.db committed yet in src/data folder. So I was not able to add encrypted items due to missing private_default.db. I was only able to test it by manually copying my local version of private_default.db to work_directory/data.

Closing old issues

Attachments:

298Del3_V4.patch