get dpl from specific branch

During a release, travis installs the dpl gem. The latest released
version is broken, the travis devs provided us a fix which is available
in a certain branch: travis-ci/dpl#487
This fix is tested in several modules, fox example zabbix, gluster,
minecraft

moduleroot/.travis.yml

@@ -53,6 +53,8 @@ notifications:
   email: false
 deploy:
   provider: puppetforge
+  deploy:
+    branch: ha-bug-puppet-forge
   user: puppet
   password:
     secure: "<%= @configs['secure'] -%>"