Regenerate yarn.lock and tweak circle config

circle.yml

@@ -5,11 +5,7 @@ machine:
     - mkdir ~/.yarn-cache
 dependencies:
   pre:
-    # Install Yarn
-    - sudo apt-key adv --fetch-keys http://dl.yarnpkg.com/debian/pubkey.gpg
-    - echo "deb http://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
-    - sudo apt-get update -qq
-    - sudo apt-get install -y -qq yarn
+    - curl -o- -L https://yarnpkg.com/install.sh | bash
   cache_directories:
     - "~/.yarn-cache"
   override: