Fixed 'noCaching' typo. Changed 'maxSize' to 'maxAge'

The `opt` object is for `node-lru-cache`'s consumption. It does this check: `this._maxAge = options.maxAge || null`.  Since there is no `maxAge` property, `this._maxAge` is getting set to `null`. This is probably the intended effect of setting `maxSize: 0`.

The `maxAge` property could be removed all together since that's essentially the way its been working, but this fix makes it explicit that there is no `maxAge`. Besides there is no `maxSize`.