bug fixes
bug fixes

1. missing model in currentTask.model.to.
2. check if task.$element exist.
GuilhouT/angular-gantt,ganquan0910/angular-gantt,hetz/angular-gantt,JJediny/angular-gantt,hetz/angular-gantt,Pandahisham/angular-gantt,Pandahisham/angular-gantt,angular-gantt/angular-gantt,ganquan0910/angular-gantt,hinablue/angular-gantt,GuilhouT/angular-gantt,fzxs8/angular-gantt,angular-gantt/angular-gantt,hinablue/angular-gantt,JJediny/angular-gantt,fzxs8/angular-gantt,angular-gantt/angular-gantt