refactor(grid): remove the old grid system

BREAKING CHANGES:

Removed the deprecated (old) grid. See the blog post for more
information including steps to migrate:
http://blog.ionic.io/build-awesome-desktop-apps-with-ionics-new-responsi
ve-grid/

Author: brandyscarney

src/components/grid/grid.old.scss

@@ -72,7 +72,6 @@
 "../components/fab/fab.wp";
 
 @import
-"../components/grid/grid.old",
 "../components/grid/grid";
 
 @import