chore: added yarn.lock files

Author: halfzebra

.travis.yml

@@ -1,31 +1,41 @@
 language: node_js
+
 sudo: required
+
 node_js:
   - '8'
   - '7'
   - '6'
+
 addons:
   apt:
     packages:
       - xvfb
+
 cache:
   yarn: true
   directories:
     - $HOME/.yarn-cachegi
+
 before_install:
   - export DISPLAY=':99.0'
   - Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
+
 install:
-  - npm install
+  - yarn install
   - cd packages/create-elm-app
-  - npm install
-  - npm link
+  - yarn install
+  - yarn link
   - cd ..
+
 script: npm test
+
 after_success:
-  - npm run semantic-release
+  - yarn run semantic-release
+
 branches:
   except:
     - /^v\d+\.\d+\.\d+$/
+
 notifications:
   email: false