ci: link yarn in /usr/local/bin after upgrade it

Author: Brooooooklyn

.circleci/config.yml

@@ -11,13 +11,13 @@ jobs:
       - checkout
       - run: echo 'export PATH=${PATH}:${HOME}/${CIRCLE_PROJECT_REPONAME}/node_modules/.bin' >> $BASH_ENV
       - run: curl --compressed -o- -L https://yarnpkg.com/install.sh | bash
-      - run: source ~/.bashrc
+      - run: sudo ln -sf ~/.yarn/bin/yarn /usr/local/bin/yarn
       - restore_cache:
           key: dependency-cache-{{ checksum "package.json" }}
       - run:
           name: yarn-with-greenkeeper
           command: |
-            yarn global add greenkeeper-lockfile@1
+            sudo yarn global add greenkeeper-lockfile@1
             yarn
       - save_cache:
           key: dependency-cache-{{ checksum "package.json" }}