function TokenTable(options) {
    assert.object(options, 'options');

    this.table = new LRU({ max: options.size || 10000 });
}
Just a wrapper over LRU that supports put/get to store token -> bucket
mappings.

@private
@class TokenTable
@param {Object} options -      an options object
@param {Number} options.size - size of the LRU