Allow the Pool to be constructed without having an internal pool created.

This is useful when extending the Pool without being able to create one at
construction time.

src/main/java/redis/clients/util/Pool.java

@@ -9,7 +9,11 @@ import redis.clients.jedis.exceptions.JedisException;
 public abstract class Pool<T> {
     protected GenericObjectPool internalPool;
 
-    protected Pool() {
+    /**
+     * Using this constructor means you have to set
+     * the internalPool yourself.
+     */
+    public Pool() {
 	this.internalPool = null;
     }