The Studio plugin: fix io.js crashes

[Morfent]

Running the server on io.js never requires es6-shim since it already
supports Maps, but doesn't support Array.from(), which this uses.

[Slayer95]

Change the condition here then I think https://github.com/Zarel/Pokemon-Showdown/blob/master/app.js#L59

EDIT: Actually, it's probably better to move away from Array.from here (or shim it ourselves), as we don't need es6-shim for anything else, and requiring it would degrade collections' performance

[monsanto]

Can you guys figure this out ASAP, I want to restart main for my other patch, it'd be nice to get this one too.

EDIT: nm I am just restarting now, this can go in later

[Morfent]

A polyfill already exists for it: https://github.com/es-shims/Array.from
I think it might be safer to stick with es6-shim for now, until io.js is included with the list of engines in package.json. Refactoring this to avoid using Array.from() can be done soon.

[Slayer95]

Now that we don't depend on es6-shim, adding it back (or another dependency) for a plugin sounds like a crime ;-;

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