Added Foundation framework and enhanced some views

- Added Spring Security tags dependency in gradle file
- Changed logout URL in SecurityConfigurer
- Revert @RequestMapping values to "" instead of nothing
  -> By default, value is not "" but "[^\.]*", so all queries are detected
     with this pattern
- Modified standard layout to use the Foundation framework
  -> Usage of the large, medium and small properties to simplify the
     creation of a responsive web design
  -> Added security check with Spring Security tags to change the
     navigation bar if the current user is connected or not
- Started to use the Foundation framework in some existing views to
  enhance them
- Added views for schools management
  -> CRUD on trainings, modules, courses and classes