Auto close drops when time is up

New option will allow you to close all started but not validated drops  when time is over or when you change the evaluation state to a state that not allow drop.

- 2 new databaseField on dropzone
- 1 new databaseField on drop.
![eval_preprod 2014-04-04 15-42-25](https://cloud.githubusercontent.com/assets/3479942/2615851/38373e5c-bbff-11e3-9da8-47d1408c9587.png)
![eval_preprod 2014-04-04 15-43-58](https://cloud.githubusercontent.com/assets/3479942/2615852/395a0bfc-bbff-11e3-8561-6007776622d3.png)


+macro correction -> case where no document was added.