Fix #83, transfers failing due to various errors

The transfers were failing due to errors. Also fixed an api issue where
the method wasn't very descriptive.

src/main/java/com/graywolf336/jail/PrisonerManager.java

@@ -732,9 +732,9 @@ public class PrisonerManager {
                     //If the targetCell has a chest
                     if(targetCell.hasChest()) {
                         //Loop through the origin's chest inventory and add it to the target cell's chest
-                        for(ItemStack i : originCell.getChest().getInventory().getContents()) {
+                        for(ItemStack i : originCell.getChest().getInventory().getContents())
+                            if(i != null)
                                 targetCell.getChest().getInventory().addItem(i);
-                        }
 
                         //Clear the origin cell's chest as it is clear now
                         originCell.getChest().getInventory().clear();

src/main/java/com/graywolf336/jail/command/subcommands/JailTransferCommand.java

@@ -65,13 +65,11 @@ public class JailTransferCommand implements Command {
         if(params.getJail() == null) {
             sender.sendMessage(Lang.PROVIDEAJAIL.get(Lang.TRANSFERRING));
             return true;
-        }else {
+        }else if(!jm.isValidJail(params.getJail())) {
             //Check if the jail they did provided is not a valid jail
-            if(!jm.isValidJail(params.getJail())) {
             sender.sendMessage(Lang.NOJAIL.get(params.getJail()));
             return true;
         }
-        }
 
         jm.getPlugin().debug("They provided a valid jail, so let's check the target cell.");
 

src/main/java/com/graywolf336/jail/events/PrePrisonerTransferredEvent.java

@@ -18,7 +18,7 @@ import com.graywolf336.jail.beans.Prisoner;
  * 
  * @author graywolf336
  * @since 3.0.0
- * @version 1.0.0
+ * @version 1.0.1
  */
 public class PrePrisonerTransferredEvent extends Event implements Cancellable {
     private static final HandlerList handlers = new HandlerList();
@@ -114,8 +114,8 @@ public class PrePrisonerTransferredEvent extends Event implements Cancellable {
     }
 
     /** Gets whether the prisoner being transferred is online or not. */
-    public boolean isOnline() {
-        return player == null;
+    public boolean isPlayerOnline() {
+        return player != null;
     }
 
     /** Gets the name of what is transferring this prisoner. */

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

@@ -75,10 +75,12 @@ public class CacheListener implements Listener {
 
     @EventHandler(priority = EventPriority.LOWEST)
     public void beforeTransferringListener(PrePrisonerTransferredEvent event) {
+        if(event.isPlayerOnline()) {
             if(pl.getJailManager().inCache(event.getPlayer().getUniqueId())) {
                 pl.getJailManager().removeCacheObject(event.getPlayer().getUniqueId());
             }
         }
+    }
 
     @EventHandler(priority = EventPriority.LOWEST)
     public void transferListener(PrisonerTransferredEvent event) {