build: reduce logs from npm install

appveyor.yml

@@ -12,7 +12,7 @@ environment:
 install:
   # install nodejs and npm
   - ps: Install-Product node $env:nodejs_version
-  - npm install -g yarn
+  - npm install -g yarn --quiet
   - yarn install --pure-lockfile --no-progress
   - npm install -g grunt-cli
   - appveyor DownloadFile https://storage.googleapis.com/golang/go%GOVERSION%.windows-amd64.zip

scripts/circle-test.sh

@@ -13,7 +13,7 @@ function exit_if_fail {
 cd /home/ubuntu/.go_workspace/src/github.com/grafana/grafana
 
 rm -rf node_modules
-npm install -g yarn
+npm install -g yarn --quiet
 yarn install --pure-lockfile --no-progress
 
 exit_if_fail npm test