added variable setting and mixins for enabling/disabling grid classes, utlized grid function to generate grid classes
fixed glitch with media queries
refactored tooltips (reduced overhead, added reset method, removed filter drop shadow) - Fixes #12
whoops, forgot to remove classes in reset method
adjustments to code/pre
changed event binding for tabs
changed event binding for tabs - Fixes #46
Merge branch 'master' of github.com-gary:groundworkcss/groundwork
enhanced use of placeholders, added media query mixins, utilizing @content
Update README.md