Fixed grid bug for wide breakpoint.
Also improved offset mixin and fixed offsetFirstChild mixin.
Merge pull request #21 from nicbell/master

Fixed grid bug for wide breakpoint.
Merge branch 'master' of https://github.com/tmwagency/kickoff into browserify

* 'master' of https://github.com/tmwagency/kickoff:
  Fixed grid bug for wide breakpoint. Also improved offset mixin and fixed offsetFirstChild mixin.