Allow options to be set globally

[kodie]

I think it would be nice if options such as --path could be set on the global command.

So something like

gpm --path content/compile.json install --save kodie/filebokz

However, I think this would be resolved by itself if my pull request to the PHP-CLI library ever gets merged in: splitbrain/php-cli#26

[kodie]

Well, my PR was denied for php-cli so we might want to look into an alternative package.