Return iso dates for everything date related from the api (#130)

Remove traces of unix timestamp

Revert renaming reminder table column

Fix staticcheck

Remove unused table call

Add migration for renaming reminders table

Fix issues with using TimeStamp

Fix lint

Updated all created / updated fields to use TimeStamps

Add comments

Convert all created / updated fields to datetime

Add time util package

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/130

pkg/models/label_task.go

@@ -17,6 +17,7 @@
 package models
 
 import (
+	"code.vikunja.io/api/pkg/timeutil"
 	"code.vikunja.io/api/pkg/user"
 	"code.vikunja.io/web"
 	"github.com/go-xorm/builder"
@@ -29,8 +30,8 @@ type LabelTask struct {
 	TaskID int64 `xorm:"int(11) INDEX not null" json:"-" param:"listtask"`
 	// The label id you want to associate with a task.
 	LabelID int64 `xorm:"int(11) INDEX not null" json:"label_id" param:"label"`
-	// A unix timestamp when this task was created. You cannot change this value.
-	Created int64 `xorm:"created not null" json:"created"`
+	// A timestamp when this task was created. You cannot change this value.
+	Created timeutil.TimeStamp `xorm:"created not null" json:"created"`
 
 	web.CRUDable `xorm:"-" json:"-"`
 	web.Rights   `xorm:"-" json:"-"`