check invalid settlement and ts time

apiV1PayIn.go

 	log "github.com/sirupsen/logrus"
 	"net/http"
 	"strconv"
+	"time"
 )
 
 func decodeJsonPayInEdit(r *http.Request) (ret loan.PayIn, e error) {
 		apiV1Client404Error(w, r, ss)
 		return
 	} else {
+		lowerBound, _ := time.Parse("2006-01-02", "1900-01-01")
+		if input.Settlement.Before(lowerBound) {
+			input.Settlement = lowerBound
+		}
+		if input.Ts.Before(lowerBound) {
+			input.Ts = time.Now()
+		}
 		e = input.Write()
 		if e != nil {
 			log.Error("cannot save basic loan", e.Error())