Theme is not set properly

[bronzle]

Theme should be set with data.theme instead of theme variable (which is undefined)
see https://github.com/Robdel12/DropKick/blob/master/jquery.dropkick.js#L433

I would have made a pull request, but running gulp on develop introduced a bunch of changes in git, when I feel like I should just be making one ... =/

[Robdel12]

Whoops! Sorry about the Gulp stuff. Fixed that too :)