message: added static button to backers list
diff: <p translate="Views.Support.BackersDetail"></p>
  <div class="backers">
  <a ng-repeat="i in 29 | range track by $index" ng-href="https://opencollective.com/dim/backer/{{$index}}/website" target="_blank"><img ng-src="https://opencollective.com/dim/backer/{{$index}}/avatar.svg"></a>
  + <a ng-href="https://opencollective.com/dim#backer">
  + <img ng-src="https://opencollective.com/public/images/become_backer.svg">
  + </a>
  </div>
  <h2 translate="Views.Support.Sponsors"></h2>
  <p translate="Views.Support.SponsorsDetail"></p>
  