Merge pull request #10 from zurb/master

Update Foundation
Fix #5155

Fix #5155. Hamburger icon has now become a pseudo-element meaning the old way of centre positioning it will not work. Updated version will work.
Merge pull request #5159 from winghouchan/fix-5155

Fix #5155
Fix for issue #5036
Merge pull request #5160 from darylprickett/issue_5036

Fix for issue #5036