Delete submitted reports

This pull request adds the possibility to delete all the reports not submitted.

## How to do it?

To do this, after uploading a report got to  trade#/annual_report_uploads and press the Delete All Button.

##How does it work?

I have created a Route for DELETE on trade/annual_report_uploads/delete_all and there is an Ajax call to it on annual_report_uploads_controller.js.coffee.

I have created a delete_all method on the annual_report_uploads_controller.rb to handle with this request.