file logging mechanism

Closes #130

See merge request !64

Resolve "Possibility to modify contact attempt comments"

Closes #132

See merge request !63

Merge remote-tracking branch 'origin/master' into 132-possibility-to-modify-contact-attempt-comments

Merge branch '139-subjects-with-flying-team-location-should-have-default-flying-team-location-defined' into 'master'

Resolve "subjects with flying team location should have default flying team location defined"

Closes #139

See merge request !62

Resolve "Export to Excel"

Closes #131

See merge request !60

Merge branch '133-possibility-to-add-appointment-from-visit-list-for-the-unfinished-visit' into 'master'

possibility to add appointment from visit list

Closes #133

See merge request !61

common data extraction code extracted

finsihed appointment types are highlighted in the visit detail view

Closes #115

See merge request !59

adding contact attempts is possible from appointment edit page

Closes #132

See merge request !58

data change should only be recognized when input is in a form

Closes #136

See merge request !57

when form data is changed clicking on navigation link require confirmation

Closes #136

See merge request !56

Resolve "worker list should be in alphabetic order"

Closes #135

See merge request !55

when editing/adding appointment only locations and workers assigned to worker location are visible, workers are sorted alphabitecally,

Resolve "Avaibility details"

Closes #17

See merge request !54