Integrates responsive css lib 'unsemantic css'

* refs #16766
Further clean up of main css file

* refs #16766
Changes styling of application form

* Kind of centralizes css for forms in form.css

* Removes table layout from application for leave form,
  uses now correct form layout instead

* refs #16766
Integrates tag for print button

* Adds print tag to have a unified print button

* Unifies tables: always use columns first name and last name

* Removes print preview page since it is not needed when the
  staff page contains all relevant information

* refs #17401
* refs #17397