Enfore precise distro or travis

Author: JamieDixon

.travis.yml

@@ -1,4 +1,6 @@
 ---
+dist: precise
+sudo: required
 language: node_js
 node_js:
   - 6
@@ -8,10 +10,6 @@ cache:
   - node_modules
   - packages/create-react-app/node_modules
   - packages/react-scripts/node_modules
-before_install:
- - rm -rf ~/.yarn
- - curl -o- -L https://yarnpkg.com/install.sh | bash
- - export PATH=$HOME/.yarn/bin:$PATH
 install: true
 script:
  - 'if [ $TEST_SUITE = "simple" ]; then tasks/e2e-simple.sh; fi'