Allow _env to check getenv as well as $_ENV

[garoevans]

No description provided.

[pmjones]

@vlucas pointed this out to me at a recent conference: https://github.com/vlucas/phpdotenv

Including that at the project level looks like it might solve our woes here.

[harikt]

good @pmjones 👍

[garoevans]

Looks nice and lightweight. Fixes my problem :)

[pmjones]

OK, so, I'm going to decline this pull request, but not because it's a bad idea or badly implemented. I have made some changes to Web_Kernel that should make this PR unnecessary. You should be able to add 'vlucas/dotenv' to your project composer file, update the projects, and then use Dotenv::load() in your _env.php file. This has the benefit of allowing any type of _env.php logic you want, Dotenv or no.