HashtableResizerTask should own reference to store

/**

 * Look around at hash tables and verify they're all sized

 * appropriately.

 */

class HashtableResizerTask : public GlobalTask {

public:

    HashtableResizerTask(KVBucketIface* s, double sleepTime); <- `s` should be reference

    bool run(void);

    cb::const_char_buffer getDescription() {

        return "Adjusting hash table sizes.";

    }

private:

    KVBucketIface* store; <- should be reference

};