chore: change default npm client to yarn

.appveyor.yml

@@ -7,13 +7,13 @@ matrix:
 
 install:
   - ps: Install-Product node $env:nodejs_version
-  - npm install -g npm
-  - npm install
+  - npm install -g yarn
+  - yarn install
 
 test_script:
   - node --version
-  - npm --version
-  - npm test
+  - yarn --version
+  - yarn test
   - node tests\run_e2e.js
 
 build: off

.gitignore

@@ -1,7 +1,6 @@
 dist/
 node_modules/
 npm-debug.log*
-yarn.lock
 
 # IDEs
 .idea/

.travis.yml

@@ -54,11 +54,12 @@ before_install:
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export CHROME_BIN=chromium-browser; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then echo "--no-sandbox" > ~/.config/chromium-flags.conf; fi
   - npm install -g npm
-  - npm config set spin false
-  - npm config set progress false
+  - npm install -g yarn
+  - yarn config set spin false
+  - yarn config set progress false
 
 install:
-  - npm install --no-optional
+  - yarn install --no-optional
 
 script:
   - if [[ "$SCRIPT" ]]; then npm run-script $SCRIPT; fi