Add .DS_Store to gitignore
Update .editorconfig to match the readme

The readme says that we are going with 2 spaces
(https://github.com/h5bp/Effeckt.css#-contributing--pull-requests) so I
updated to .editorcofig to match so we are all on the smae page
Merge pull request #67 from bryanstedman/master

Small tweaks to dotfiles