deposit: datetime picker library modification

* Changes the datetime picker library from the jQuery UI to https://github.com/Eonasdan/bootstrap-datetimepicker.

* Increases the consistency with the Bootstrap design.
I would leave it as it was before so that the transition is seamless from the previous datepicker for sites like Zenodo.

Then in our overlay ```run.html``` we can tweak the options as we want, adding for example that one.