Shadow client field from PipelineBlock and TransactionBlock

* it prevent from user accessing BinaryClient, while it is not treated to pipeline command
** it could make troubles when reading responses

src/main/java/redis/clients/jedis/PipelineBlock.java

@@ -2,5 +2,9 @@ package redis.clients.jedis;
 
 
 public abstract class PipelineBlock extends Pipeline {
+	// For shadowing
+	@SuppressWarnings("unused")
+	private Client client;	
+	
     public abstract void execute();
 }