Don't edit the jail signs async, as that is bad and causes #36.

This should fix the Asynchronous entity world add exception being thrown

src/main/java/com/graywolf336/jail/listeners/CellSignListener.java

@@ -5,6 +5,7 @@ import java.util.List;
 
 import org.bukkit.block.Sign;
 import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 
 import com.graywolf336.jail.JailMain;
@@ -19,17 +20,21 @@ import com.graywolf336.jail.events.PrisonerTransferredEvent;
 
 public class CellSignListener implements Listener {
     private String lineOne, lineTwo, lineThree, lineFour;
+    private JailMain pl;
 
     public CellSignListener(JailMain plugin) {
-        List<String> lines = plugin.getConfig().getStringList(Settings.CELLSIGNLINES.getPath());
+        pl = plugin;
+        List<String> lines = pl.getConfig().getStringList(Settings.CELLSIGNLINES.getPath());
         lineOne = lines.get(0);
         lineTwo = lines.get(1);
         lineThree = lines.get(2);
         lineFour = lines.get(3);
     }
 
-    @EventHandler
-    public void changeTheCellSigns(PrisonerTimeChangeEvent event) {
+    @EventHandler(ignoreCancelled=true, priority = EventPriority.MONITOR)
+    public void changeTheCellSigns(final PrisonerTimeChangeEvent event) {
+        pl.getServer().getScheduler().scheduleSyncDelayedTask(pl, new Runnable() {
+            public void run() {
                 if (event.hasCell() && event.getCell().hasSigns()) {
                     HashSet<SimpleLocation> signs = event.getCell().getSigns();
                     String s1 = Util.replaceAllVariables(event.getPrisoner(), lineOne);
@@ -53,6 +58,8 @@ public class CellSignListener implements Listener {
                     }
                 }
             }
+        });
+    }
     
     @EventHandler
     public void changeCellSignsOnJail(PrisonerJailedEvent event) {