fs.exists is being deprecated

[markstos]

fs.exists is used a few places in the code base, but is being deprecated by node and io.js and is not recommended by the current official Node.js docs.

Alternatives include using fs.stat or just skipping the check, trying a file action, and handing the error if it doesn't exit.

Refactoring to avoid fs.exists now would provide a bit of future-proofing.

[ErisDS]

@markstos thanks for the headsup :)

I think the places where we use fs.exists (namely image storage) will need to switch to use fs.stat as the pre-check is used to generate a unique filename before saving.

[jxhn]

I'm aware it's not super urgent but I wouldn't mind jumping in on this.