remove unused fields
CLUSTER FAILOVER : failover manually (from slave)

* usage : CLUSTER FAILOVER
* node will try to demote its master and promote to master
* Unit test included "but set to @Ignore"
** Be careful!! There's some error on cluster failover (manual failover failed)
** tested Redis version : 0f2597092fdcd17547282bd434e46d3dc8412e23
Fix JedisClusterTest : forget all nodes after running all tests

* It affects JedisClusterReplicateTest
Fix unit test : sometimes cluster slaves report there're no slave but I've checked first
Add FIXME : it's too slow to run... but we cannot apply pipeline now