[ADD] slides gallery module

- Task: https://www.odoo.com/web?#id=9093&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.QlQTvBv6mCcMrK4B
select2 Bootstrap 3 css v1.4.1 is bootstrap wrapper for Select2
This wrapper v1.4.1 is Tested with Bootstrap v3.2.0 and Select2 v3.3.2, v3.4.1-v3.4.5, v3.5.1, master
https://fk.github.io/select2-bootstrap-css/