add podAntiAffinity

this MR adds a podAntiAffinity to pods generated by the same Deployment or DeploymentConfig unless we have volumes with ReadWriteOnce involved (in which case we still use a podAffinity rule). This make the application more fail-safe as it still works if one node is shutdown. Note that this can only work with pods that use ReadWriteMany volumes

ping @jan-eike.schnabel