Implemented FlySystem for FileSystem abstraction

[dubcanada]

Solves #41

I wasn't exactly sure if this is the best method or not, but it works. Basically I took out the FileStorage interface and replaced it with FlySystem.

[scottrobertson]

Thanks for this, shall take a look at it today.

[scottrobertson]

Sorry, been very busy. @codeguy can you take a look at this too?

[scottrobertson]

I am happy with this as a first step i think.

[dubcanada]

Thoughts?

[codeguy]

I like. @scottrobertson what else do you have in mind?

[scottrobertson]

We should pick this up again, sorry i did not respond. Is this still ok to merge?

[bradleyboy]

Coming to this late but one thing to watch out for here is that FlySystem requires PHP 5.4+, while this library is currently baselined at 5.3.

[codeguy]

@bradleyboy Good point. I'm fine bumping the requirements. I'll do that shortly.

[doorhinge]

@codeguy any update on this?

[doorhinge]

@codeguy Not to be annoying, but I'm really interested in using this with Flysystem, so I'm just wondering if you plan on merging this? Thanks :smile:

[mikealmond]

Any update on this PR?

[tamtamchik]

:+1: any ETA when this could possibly be implemented?

[jeremykendall]

Bump.

[kaperys]

Any update on this?

[napolux]

Hellooooooo.... Is this repo still active?

[solleer]

Will this be merged