Local node incorrectly resolved on Windows

[connorjsmith]

Disclaimer: I am not that experienced with cmd scripting

After updating to the latest npm, some of our scripts broke. I traced this to the change in #26, which always quotes the executable name (even if it is just node). This seems to cause issues for some paths (The system cannot find the path specified.)

Proposed fix (using tslint as an example):

@ECHO off
SETLOCAL
CALL :find_dp0

SET _maybeQuote="
IF EXIST "%dp0%\node.exe" (
  SET "_prog=%dp0%\node.exe"
) ELSE (
  SET "_prog=node"
  SET _maybeQuote=
  SET PATHEXT=%PATHEXT:;.JS;=;%
)

%_maybeQuote%%_prog%%_maybeQuote%  "%dp0%\..\tslint\bin\tslint" %*
ENDLOCAL
EXIT /b %errorlevel%
:find_dp0
SET dp0=%~dp0
EXIT /b

For the %dp0% case, this resolves to
"%dp0%\node.exe" "%dp0%\..\tslint\bin\tslint" %*
otherwise, it resolves to
node "%dp0%\..\tslint\bin\tslint" %*

Effectively, we only use quotes around the node executable when we use .bin\node.exe