.editorconfig

[lyzadanger]

This PR puts an .editorconfig in everyone's ~/ except for @tylersticka who I want to talk to first before assuming I can just trounce his existing .editorconfig.

• There is a new module: cloudfour_potions::dotfiles which I've included in everyone's personal module for now (again, except Tyler). Right now all it does is establish an .editorconfig.
• I have uncommented the editorconfig package in the cloudfour_potions::atom potion to make sure it gets installed for atom users. It had been erroring out at me transiently a few months ago, which is why comments. I believe it was intermittent issues with the package repository on Atom's end.
• Sublime users have already been getting an editorconfig package.

This is part one of some convention enforcement. Next steps are JSHint, JSRC and CSS linting.

[lyzadanger]

I should note that cloudfour_potions::dotfiles can coexist with homeshick-managed dotfiles; it will simply trounce any .editorconfig you have in your own dotfiles repo.