message: resolved issue 932
diff: <div class="col s6 m3 l3">
  <my-user-avatar [user]="user"></my-user-avatar>
  <div class="username">{{user.userName}}</div>
  + <div class="username" *ngIf="user.chatUsername">
  + <a class="mdi mdi-slack mdi-24px" name="slack" href="https://code4socialgood.slack.com/messages/@{{user.chatUsername}}/" target="_blank"></a>
  + </div>
  +
  <div class="links-list-wrapper" *ngIf="authService.authenticated()">
  <ul>
  <li><a class="mdi mdi-email" [class.not-active]="!user.email" href="mailto:{{user.email}}"></a></li>
  