i still don't know why we're still using travis (#13817)

.travis.yml

@@ -11,6 +11,7 @@ install:
   - pip install flake8==3.3.0
   - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
   - sudo rm /etc/apt/sources.list.d/docker.list
+  - sudo apt-get install hhvm && rm -rf /home/travis/.kiex/
   - sudo apt-get purge -y mysql-common mysql-server mysql-client
   - nvm install v7.10.0
   - wget https://raw.githubusercontent.com/frappe/bench/master/playbooks/install.py