Remove cache because of missing deps in win32 build

appveyor.yml

@@ -3,16 +3,13 @@ version: 0.1.{build}
 platform:
   - x64
 
-cache:
-  - '%USERPROFILE%\.electron'
-
 init:
   - git config --global core.autocrlf input
 
 install:
   - ps: Install-Product node 6 x64
   - git reset --hard HEAD
-  - npm install npm -g
+  - nvm install 6
   - npm install electron-builder@next # force install next version to test electron-builder
   - npm install
   - npm prune