message: add 'no group' as option
diff: <h3 class="mdl-dialog__title">{{ 'SELECT_AFFINITY_GROUP' | translate }}</h3>
  <div *loading="!affinityGroups" class="mdl-dialog__content">
  - <mdl-select *ngIf="affinityGroups?.length; else noGroups" [(ngModel)]="selectedAffinityGroup">
  + <mdl-select
  + *ngIf="affinityGroups?.length || vm.affinityGroup?.length; else noGroups"
  + [(ngModel)]="selectedAffinityGroup"
  + >
  + <mdl-option *ngIf="vm.affinityGroup.length" value="">{{ 'NO_GROUP' | translate }}</mdl-option>
  <mdl-option *ngFor="let ag of affinityGroups" [value]="ag.id">
  {{ ag.name }}
  </mdl-option>
  <div class="mdl-dialog__actions">
  <button
  (click)="changeAffinityGroup()"
  - [disabled]="!selectedAffinityGroup"
  + [disabled]="selectedAffinityGroup == null"
  mdl-button
  mdl-colored="primary"
  >
  