Make RedisCluster.Builder configurable

[fmonniot]

Right now the RedisCluster.Builder have some hardcoded values:

builder.setting("cluster-enabled yes");
builder.setting("cluster-config-file nodes-" + port + ".conf");
builder.setting("cluster-node-timeout 2000");
builder.setting("appendonly yes");
builder.setting("dbfilename dump-" + port + ".rdb");

Those should be configurable via the Builder interface.