Update growlFactory.js
Update growlFactory.js

On responseError data is null, and an error is raised.
JanStevens/angular-growl-2,eborned/angular-growl-2,chasemgray/angular-growl-2,vmpl/angular-growl-2,clamstew/angular-growl-2,vmpl/angular-growl-2,JanStevens/angular-growl-2,clamstew/angular-growl-2,waysay/angular-growl-2,waysay/angular-growl-2,chasemgray/angular-growl-2,eborned/angular-growl-2