code: function get(id, callback) {
          _getSHA(id, function(err, sha) {
              if (err) return callback(err);
              repo.git.blobs(sha).fetch(function(err, res) {
                  if (err) return callback(err);
                  callback(err, JSON.parse(atob(res.content)));
              });
          });
      }
docs: Get an item from the database given its id and a callback.
  
  @param {String} id
  @param {Function} callback called with (err, contents): contents
  are given as parsed JSON