Fix a bug with Vault Economy not found in loading process.

If plugin that enables Vault do it after BentoBox, then a lot of addons disabled their economy settings. This should fix it.

src/main/java/world/bentobox/challenges/ChallengesAddon.java

@@ -57,11 +57,6 @@ public class ChallengesAddon extends Addon {
 
     private boolean hooked;
 
-    /**
-     * This boolean indicate if economy is enabled.
-     */
-    private boolean economyProvided;
-
     /**
      * VaultHook that process economy.
      */
@@ -219,11 +214,10 @@ public void onEnable() {
             if (!vault.isPresent() || !vault.get().hook())
             {
                 this.vaultHook = null;
-                this.logWarning("Economy plugin not found so money options will not work!");
+                this.logWarning("Vault plugin not found. Economy will not work!");
             }
             else
             {
-                this.economyProvided = true;
                 this.vaultHook = vault.get();
             }
 
@@ -531,7 +525,7 @@ public Settings getChallengesSettings()
      */
     public boolean isEconomyProvided()
     {
-        return this.economyProvided;
+        return this.vaultHook != null && this.vaultHook.hook();
     }