matsumoto-r/mruby-redis — pull request #6 by suzukaze (2013-11-18 15:49:42+00:00)
Title: Add Redis#zadd, Redis#zrange, Redis#zrevrange, Redis#zrank

Actually ZADD command can have multi sorted sets:
```
ZADD key score member [score member]
```
Redis#zadd can have a sorted set as an arguement but cannot have multi sorted sets.
In the future I want to implement multi sorted sets.