Update to suport plugin usage in vendor package

[TerrePorter]

I was using the plugin in a package, and it was not processing the packages include_files options.

I've updated the code to allow it to work from inside a vendor packages.

[hopeseekr]

Well, looks like I'm going to fork this project, just to get this PR merged.

[hopeseekr]

@TerrePorter Thank you so much for your contribution!

I registered my fork at 0.0.0/composer-include-files so composer will, by default, load it first if it's first in the composer.json.

Here it is in action: https://github.com/phpexpertsinc/Laravel57-env-polyfill

[ivanvermeyen]

Thanks @TerrePorter and @hopeseekr !
You just saved me a giant headache :)
I'm using 0.0.0/composer-include-files and it works great! 👍

[hopeseekr]

We've got over 40,000 installs now!

@TerrePorter, your patch is changing the world!