Merge pull request #2118 from f111fei/master

'scripts\npm install' bugs in windows7

scripts/npm.bat

@@ -2,7 +2,7 @@
 setlocal
 
 set npm_config_disturl="https://atom.io/download/atom-shell"
-for /f "delims=" %%A in ('powershell -Command "(Get-Content -Raw %~dp0..\package.json | ConvertFrom-Json).electronVersion"') do set "npm_config_target=%%A"
+for /f "tokens=2 delims=:, " %%a in ('findstr /R /C:"\"electronVersion\":.*" %~dp0..\package.json') do set npm_config_target=%%~a
 set npm_config_arch="ia32"
 set HOME=~\.electron-gyp