changes to the responsive grid to make it responsive ltr and rtl

Changes made to:
index.html - adding of the dir (direction attribute) and class.

_global.scss - added the two classes ltr & rtl for the direction of content flow and the unicode-bidi to allow the ability to mix arabic and english content into the same flow.

_choreographic-grid.scss - added font-size: 0; to g-row fix the default spacing of the display: inline-block on the child elements (g-col) http://davidwalsh.name/remove-whitespace-inline-block;

_choreographic-grid-helpers.scss - changed the columns to use display:inline-block and removed floats as floats turn elements into blocked one therefore not allowing the browser to change the flow of the RWD grid from ltr to rtl.