Add support for zCard to ZSetOperations [DATAREDIS-284]

[spring-projects-issues]

Christoph Strobl opened DATAREDIS-284 and commented

zCard is available on RedisConnection but not exposed for usage via ZSetOperations.

Long zCard(K key); should be available

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Reference URL: http://stackoverflow.com/questions/22468640/how-stringredistemplate-use-redis-zcard-method

Referenced from: pull request #55