sicknote detail, added print functionality

* added print button
* print css for sick note
* further improvement of print layout for application detail and
  personal overview

* refs #14837
security fix, at least authenticated for sick note purposes

refs #14840
nav bar, sick notes point now as dropdown

* implemented functionality to show the sick notes of the last 3 months
* implemented functionality to show the sick notes of this year

* refs #14840
fix exception, if apply for 24th Dec. or 31st Dec. for half day

* refs #14898
navigate from overview datepicker to application, added link for 'free' days

* refs #14788
fix calculation vacation days, tried to fix error

* adjusted test cases for half month resp. full month
* fixed hard code error (28 days has been hard coded as year
  entitlement)

* refs #14838