PSR4 Namespace & array of paths

[stanlemon]

This PR does two things...

1. Switches over to psr4 and a namespace as @pmjones suggests in issue PSR-4 Compliance? #14
2. Added the ability to pass an array of paths instead of just one, essentially enabling fallback overrides in env paths

[vlucas]

I actually want the namespace to be Dotenv, so the class would be Dotenv\Loader or something like that.

[pmjones]

/me nods

The only counter-argument I have is that there may be other Dotenv implementations out there, either now or later, who also name themselves "Dotenv." The top-level namespace needs to be a little more unique.

[vlucas]

I think that argument can be made for almost any package market, and is predominately a "first come, first served" basis.

[pmjones]

True. I would follow it up with the idea that you personally are probably above the hoi-polloi regarding this and other topics. ;-)

[stanlemon]

I don't have a problem with Dotenv\Dotenv, if that's what you want to do I'll gladly update my PR. Let me know. Thanks.

[stanlemon]

I'll resubmit for the namespace change without the array path change if you let me know what your preference is.