split global.scss into partials

folder for base (essential) partials, modular partials, and plugin partials (so plugin styles can be deleted if they're deleted)

Signed-off-by: Erica <e@energy7.com>
un-center intro text on global

Signed-off-by: Erica <e@energy7.com>
center group intro-text, delete unused files /sass/style.scss and /css/style.css

Signed-off-by: Erica <e@energy7.com>