add varible date format (ktt-ol#11)

* Update README.md

* add DATE-FORMAT

* add varible date format

Author: mm-chen

example.cfg

@@ -37,3 +37,5 @@ broker = mqtt.server.exaple.com
 topic = /exaple/topic
 displayOn = open
 displayOff = close
+[DATE-FORMAT]
+format = %Y-%m-%d

src/curses-ui/clock.vala

@@ -18,6 +18,8 @@ using Curses;
 public class ClockWindow {
 	AsciiNumbers ascii;
 	Window win;
+	string dateformat;
+	Config cfg;
 
 	public ClockWindow() {
 		ascii = new AsciiNumbers();
@@ -26,6 +28,9 @@ public class ClockWindow {
 
 		win.clrtobot();
 		win.box(0, 0);
+		
+		cfg = Bus.get_proxy_sync(BusType.SYSTEM, "io.mainframe.shopsystem.Config", "/io/mainframe/shopsystem/config");
+		dateformat = cfg.get_string("DATE-FORMAT", "format");
 
 		win.refresh();
 	}
@@ -63,7 +68,7 @@ public class ClockWindow {
 		win.clrtobot();
 		win.box(0, 0);
 
-		win.mvaddstr(5,4, now.format("%Y-%m-%d"));
+		win.mvaddstr(5,4, now.format(dateformat));
 
 		win.refresh();
 	}