finish = function (value) {
        DEBUG && console.timeEnd("loadDatabase");
        that.operationInProgress = false;
        callback(value);
      }
Retrieves a serialized db string from the catalog.

@example
// LOAD
var idbAdapter = new IncrementalIndexedDBAdapter();
var db = new loki('test', { adapter: idbAdapter });
db.loadDatabase(function(result) {
  console.log('done');
});

@param {string} dbname - the name of the database to retrieve.
@param {function} callback - callback should accept string param containing serialized db string.
@memberof IncrementalIndexedDBAdapter