Fix npe after register.

src/main/java/fr/xephi/authme/cache/limbo/LimboCache.java

@@ -117,7 +117,10 @@ public class LimboCache {
      * @param name String
      */
     public void deleteLimboPlayer(String name) {
-        cache.remove(name);
+        if(cache.containsKey(name)) {
+            cache.get(name).clearTask();
+            cache.remove(name);
+        }
     }
 
     /**
@@ -148,8 +151,9 @@ public class LimboCache {
      * @param player Player
      */
     public void updateLimboPlayer(Player player) {
-        if (this.hasLimboPlayer(player.getName().toLowerCase())) {
-            this.deleteLimboPlayer(player.getName().toLowerCase());
+        String name = player.getName().toLowerCase();
+        if (hasLimboPlayer(name)) {
+            deleteLimboPlayer(name);
         }
         addLimboPlayer(player);
     }

src/main/java/fr/xephi/authme/cache/limbo/LimboPlayer.java

@@ -108,8 +108,9 @@ public class LimboPlayer {
      * @param i BukkitTask
      */
     public void setTimeoutTaskId(BukkitTask i) {
-        if (this.timeoutTaskId != null)
+        if (this.timeoutTaskId != null) {
             this.timeoutTaskId.cancel();
+        }
         this.timeoutTaskId = i;
     }
 
@@ -128,11 +129,27 @@ public class LimboPlayer {
      * @param messageTaskId BukkitTask
      */
     public void setMessageTaskId(BukkitTask messageTaskId) {
-        if (this.messageTaskId != null)
+        if (this.messageTaskId != null) {
             this.messageTaskId.cancel();
+        }
         this.messageTaskId = messageTaskId;
     }
 
+    /**
+     * Method clearTask.
+     *
+     */
+    public void clearTask() {
+        if (messageTaskId != null) {
+            messageTaskId.cancel();
+        }
+        messageTaskId = null;
+        if (timeoutTaskId != null) {
+            timeoutTaskId.cancel();
+        }
+        timeoutTaskId = null;
+    }
+
     /**
      * Method isFlying.
      *