Fixing CSS Typo
Merge pull request #19 from mattclements/master

Fixed CSS Typo for Foundation Integration
Fix thread 15450 - TableTools collection button can spawn multiple
backgrounds

- Due to a z-indexing error, the background element could actually be
  created multiple times by clicking on the element without moving the
  mouse. Adding a z-index statement fixes this.
Merge branch 'master' of github.com:DataTables/Plugins