[TIMOB-19673] windowslib: visualstudio.detect failed for VS 2015

PS > npm run-script test-visualstudio

> windowslib@0.1.15 test-visualstudio windowslib
> mocha --require test/init --reporter spec --check-leaks test/test-visualstudio



  visualstudio
    √ namespace should be an object
    1) detect should find Visual Studio installations


  1 passing (500ms)
  1 failing

  1) visualstudio detect should find Visual Studio installations:
     Uncaught AssertionError: expected null to be a string
      at Assertion.fail (windowslib\node_modules\should\lib\assertion.js:113:17)
      at Assertion.prop.(anonymous function) [as String] (windowslib\node_modules\should\lib\ass
ertion.js:39:14)
      at checkVisualStudio (windowslib\test\test-visualstudio.js:73:42)
      at windowslib\test\test-visualstudio.js:34:4
      at finalize (windowslib\lib\visualstudio.js:64:4)
      at windowslib\lib\visualstudio.js:218:5
      at done (windowslib\node_modules\async\lib\async.js:132:19)
      at windowslib\node_modules\async\lib\async.js:32:16
      at windowslib\lib\visualstudio.js:187:10
      at ChildProcess.<anonymous> (windowslib\node_modules\node-appc\lib\subprocess.js:60:3)
      at ChildProcess.EventEmitter.emit (events.js:98:17)
      at maybeClose (child_process.js:753:16)
      at Process.ChildProcess._handle.onexit (child_process.js:820:5)

output from console.log(vcvarsall);
C:\PROGRA~2\Microsoft Visual Studio 14.0\VC\vcvarsall.bat