Added anti-affinity feature to Heat engine

* Now it's possible to create/scale custer with Heat engine and anti-affinity feature for node
  processes
* Changed ClusterTemplate class in heat engine. Now it takes whole
  cluster object during initializing
* Also ClusterTemplate object takes node group extras like userdata
* Added unit-tests for aa during cluster creation
* In addition raised bug #1268610 about scailing cluster with
  anti-affinity process devided into two node groups

Implements: blueprint aa-heat
Partial-Bug: #1259174
Change-Id: If2927877f1ca3f7390fbf5b44929663d089f3382
Merge "Added anti-affinity feature to Heat engine"