Cluster security and node placement control

Adding user key to the cluster

Each cluster will have a it own private key for passwordless login

It is possible to schedule a data nodes on diffirent hosts

implements: blueprint node-placement-control and blueprint cluster-security

fixed: bug #1179815 and bug  #1179821

Change-Id: I27183b9fcf1652b8f65a7018fe9cb880d5bed3b3