Adds higher-level methods to dynamo-table.
Batch writes items ensuring that at most a fraction of the table's write capacity corresponding to capacityRatio is used.
Truncates table
Adds new record to the table. If record[key] is defined then the method does put straight away.
Otherwise it assigns new id and puts it to the table. Table key must be numeric. Assumes that
this.nextId (from dynamo-table-id package) is available.
Thanks to @mhart for dynamo-table upon which this extension is based.
