Ref #227, Display content access statistics.

This Pull request brings a way to show the access statistics in the interface for items: event viewing, event content download stats, grade book views, document sharing views/downloads. It also cleans up the history_log() done in the learning events section, with an entry now created when the event is created, either through add, copy, or draft. In the past the changes weren't logged until a second person worked on the event.

Once the document share changes get pulled into develop, I'll have to merge this branch again as the shares merge with the statistics always caused problems over here at UCLA.