* simplifying edx.org breakpoints to use min-width * creating -bp-* centric Sass variables * converting all existing edx.org centric media queries to use new Sass variables ECOM-1457
* simplifying edx.org breakpoints to use min-width * creating -bp-* centric Sass variables * converting all existing edx.org centric media queries to use new Sass variables ECOM-1457