fixed drag method call to check first

to avoid a "cannot call methods on draggable prior to initialization; attempted to call method 'disable'" error on fullScreen toggle, in case of a non-drag(gable) <div id="cont3" class="container" data-collapse=true data-close=true data-containment="document" data-modal=true> call and latest jQuery and JQuery-UI
Merge pull request #8 from ophian/master

drag fix