fix https://github.com/zstackorg/zstack/issues/219.
fix https://github.com/zstackorg/zstack/issues/219.

zstack-ctl install_management_node will install ansible as well.

zstackorg/zstack-utility,live4thee/zstack-utility,zstackorg/zstack-utility,mingjian2049/zstack-utility,zstackorg/zstack-utility,mrwangxc/zstack-utility,zstackio/zstack-utility,live4thee/zstack-utility,live4thee/zstack-utility,mingjian2049/zstack-utility,mrwangxc/zstack-utility,mrwangxc/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility,mingjian2049/zstack-utility