Update appveyor to use yarn instead of npm and auto fix windows line endings

Author: DaRamirezSoto

appveyor.yml

@@ -1,21 +1,24 @@
 cache:
   - node_modules
+  - "%LOCALAPPDATA%\\Yarn"
+
+init:
+  - git config --global core.autocrlf true
 
 environment:
-  matrix:
-    - nodejs_version: "6"
+  nodejs_version: "6"
 
 platform:
   - x86
   - x64
 
 install:
   - ps: Install-Product node $env:nodejs_version $env:platform
-  - npm install
+  - yarn
 
 test_script:
   - node --version
-  - npm --version
-  - npm run test
+  - yarn --version
+  - yarn run test
 
 build: off