CBQE-1095 enable xdcr setup in systest manager

We can setup xdcr replication by doing this:
    "phases" : {
                "0" :
                {
                    "name" : "xdcr setup",
                    "xdcr" : {"dest_cluster_rest_username": "Administrator", "dest_cluster_rest_pwd": "password",
                              "dest_cluster_name": "remote1", "replication_type": "bidirection"}
                  }
}

Change-Id: I71ddf56b3cb496a6d1718facd2a37505c2177860
Reviewed-on: http://review.couchbase.org/25627
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Tommie McAfee <tommie@couchbase.com>