Add Skin browser to SFP

[PhantomGamers]

Skin authors should be able to add their skins to some database that SFP polls, displaying all of the possible skins with a preview image.

Skins should have a name, description, an author field, and a link to the original project.

Problems that need to be solved:

• If users are able to install skins with javascript files directly from SFP there needs to be some way to make sure that malicious code is never distributed. Maybe JS support will be disabled from skins obtained through the browser, but then this limits the usefulness of this feature.
• How will the database be managed? I suppose it'd probably just be its own github repo where authors can submit pull requests to add their own skins to the repo.

[Bread-Ch4n]

https://github.com/PhantomGamers/SFP/pull/197