Fix json time when unmarshalling

https://github.com/stashapp/stash/issues/25

pkg/models/json_time.go

@@ -0,0 +1,30 @@
+package models
+
+import (
+	"fmt"
+	"github.com/stashapp/stash/pkg/utils"
+	"strings"
+	"time"
+)
+
+type JSONTime struct {
+	time.Time
+}
+
+func (jt *JSONTime) UnmarshalJSON(b []byte) (err error) {
+	s := strings.Trim(string(b), "\"")
+	if s == "null" {
+		jt.Time = time.Time{}
+		return
+	}
+
+	jt.Time, err = utils.ParseDateStringAsTime(s)
+	return
+}
+
+func (jt *JSONTime) MarshalJSON() ([]byte, error) {
+	if jt.Time.IsZero() {
+		return []byte("null"), nil
+	}
+	return []byte(fmt.Sprintf("\"%s\"", jt.Time.Format(time.RFC3339))), nil
+}