mail with kit request doesn't persist new worker

Closes #171

See merge request NCER-PD/scheduling-system!98

Resolve "appointment date change"

Closes #172

See merge request NCER-PD/scheduling-system!97

Resolve "generating from mail templates"

Closes #165

See merge request NCER-PD/scheduling-system!96

appointment can be removed, but only when not atached to visit and with SCHEDULED status

Closes #150

See merge request NCER-PD/scheduling-system!95

list of appointments contains information about availabilities

Closes #143

See merge request NCER-PD/scheduling-system!94

validation of nd number added

Closes #148

See merge request NCER-PD/scheduling-system!93

when exporting there is artifitial column that marks dropped out subjects

Closes #156

See merge request NCER-PD/scheduling-system!92

subject contain resign reason field (obligatory when marking subject as resigned)

Closes #155

See merge request NCER-PD/scheduling-system!91

resolution improved

Closes #168

See merge request NCER-PD/scheduling-system!90

edit button in list of subjects is standard 'a' tag

Closes #149

See merge request NCER-PD/scheduling-system!89

list of countries is provided as predefined list

Closes #170

See merge request NCER-PD/scheduling-system!88

in daily planning user can schedule non-subject related appointments

Closes #160

See merge request NCER-PD/scheduling-system!87

Resolve "follow up visits should be based on visit one date"

Closes #169

See merge request NCER-PD/scheduling-system!86

subject list contain list of visits

Closes #140

See merge request NCER-PD/scheduling-system!85