title: Add file via button using Dropzone plugin
body: <p>Is it possible to use an external button to add file using Dropzone plugin?
  I found this <a href="https://github.com/enyo/dropzone/wiki/Upload-all-files-with-a-button" rel="nofollow">documentation</a> but it doesn't answer my question.Indeed, I can't be able to add file using an handler event such as click. Is there a solution?</p>