Implemeted abstract Task class

* Removes the duplicated code in every Task class.

src/me/mrCookieSlime/Slimefun/Objects/tasks/SlimefunTask.java

@@ -0,0 +1,31 @@
+package me.mrCookieSlime.Slimefun.Objects.tasks;
+
+import org.bukkit.Bukkit;
+
+import java.util.UUID;
+
+public abstract class SlimefunTask implements Runnable {
+    private UUID uuid;
+    private int id;
+
+    @Override
+    public void run() {
+        if(cancelTask())
+            return;
+        executeTask();
+    }
+
+    /**
+     *
+     * @return True if task was cancelled.
+     */
+    private boolean cancelTask(){
+        if(Bukkit.getPlayer(uuid) == null || Bukkit.getPlayer(uuid).isDead() || !Bukkit.getPlayer(uuid).isSneaking()) {
+            Bukkit.getScheduler().cancelTask(id);
+            return true;
+        }
+        return false;
+    }
+
+    abstract void executeTask();
+}