Windows batch file does not check for custom INI file

Drush doesn't check for custom INI files in the Windows batch file, like it does in the shell script.

I added a simple if statement to the batch file drush.bat that checks to see if there is a Drush.ini file in the main drush install directory, and if found it uses it. This is not super elegant, but it worked for me, and allowed me to disable open_basedir restrictions for Drush, while leaving it in place in my main php.ini file.

IF EXIST "%~dp0drush.ini" (
	 @php.exe -c "%~dp0drush.ini" "%~dp0drush.php" %* --php="php.exe"
) ELSE (
	@php.exe "%~dp0drush.php" %* --php="php.exe"
)