Build: Improve AppVeyor build

Author: sttk

appveyor.yml

@@ -15,6 +15,8 @@ environment:
     - nodejs_version: "5"
 
 install:
+  - IF %nodejs_version% EQU 0.10 npm -g install npm@2
+  - IF %nodejs_version% EQU 0.10 set PATH=%APPDATA%\npm;%PATH%
   - ps: Install-Product node $env:nodejs_version
   - npm install