[Bugfix: windows] Allow paratest to work even when paths contain spaces

Hello,

When attempting to run paratest on windows I was repeatedly getting `"Log file XYZ is empty. This means a PHPUnit process has crashed.`. After a bit of debugging it turns out this was due to phpunit being passed options (such as paths) that contained spaces.

I've added a fix that effectively just encases the option values in quotes in order to resolve this issue. Everything appears to be working normally for me now so i thought I may I may as well put in a pull with the fix.

Thanks,
Carl