Features

• Rank items from collaborative filternig by click-through-rate prediction to improve recommendation accuracy (#17).
• Address cold-start problem by inserting latest items to the result from collaborative filternig (#151).
• Disable click-through-rate prediction when labels are unavaliable.
• Enable RESTful server logging.

Fix

• Error 1069: Too many keys specified; max 64 keys allowed (#176).
• Panic on unknown users and items (#185).
• lastNumUsers, lastNumItems, lastNumFeedback always zero (#197).
• Documents has been updated (#180).