Support for L.Control.Zoomslider

http://kartena.github.io/Leaflet.zoomslider/
Support for L.Control.Zoomslider

http://kartena.github.io/Leaflet.zoomslider/
Removed needless check, corrected indentation
Merge pull request #14 from kermit-the-frog/master

Support L.Control.Zoomslider