Fixed ical-go package include

vendor/github.com/laurent22/ical-go/calendar.go

@@ -0,0 +1,17 @@
+package ical
+
+type Calendar struct {
+	Items []CalendarEvent
+}
+
+func (this *Calendar) Serialize() string {
+	serializer := calSerializer{
+		calendar: this,
+		buffer:   new(strBuffer),
+	}
+	return serializer.serialize()
+}
+
+func (this *Calendar) ToICS() string {
+	return this.Serialize()
+}