Added Responsive Boilerplate

Responsive Boilerplate is a great starting point to responsive web design.

"A lightweight (2kb) micro-framework, elegant & minimalistic CSS3 grid system, made with only three main classes and 12 columns. It`s very easy to use and understand, pre-packed with some extra css helpers for mobile devices."
Merge pull request #75 from rictorres/patch-1

Added Responsive Boilerplate