optimize the partition distribute algorithm

[baotiao]

In current version, the partition distribute algorithm has some problems, such as we can't not allot every node the same number of partition, we can only promise that the 3 copies not be put in same node, but we can't not promise that any two copy will not be put in same machine, since there is many nodes in a machine.

we need improve the partition distribute algorithm, the most elaborate dirstribute algorithm I have seen is ceph's crush algorithm. Maybe we can copy this algorithm and implement it in zeppelin