Grunt fails on psg-theme-default via grunt-postcss
Grunt fails on psg-theme-default via grunt-postcss

- Move `default` theme to devDependencies so Grunt references module in expected location `node_modules/postcss-style-guide/node_modules/psg-theme-default`
seka/postcss-style-guide,morishitter/postcss-style-guide,seka/postcss-style-guide,morishitter/postcss-style-guide