implemented bitcount and bitop commands for Redis 2.6

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

@@ -285,4 +285,10 @@ public interface Commands {
     public void objectIdletime(String key);
 
     public void objectEncoding(String key);
-}
+
+    public void bitcount(final String key);
+
+    public void bitcount(final String key, long start, long end);
+
+    public void bitop(BitOP op, final String destKey, String... srcKeys);
+}