Introduce *scan with "string" cursor parameter to support unsigned long

cursor

* overload all *scan method to change "int" cursor to "string" cursor
* set @Deprecated and leave reason to deprecate and when to remove to
current *scan method
* modify unit tests to make it work with new *scan method

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

@@ -70,5 +70,13 @@ public interface MultiKeyCommands {
 
     Long bitop(BitOP op, final String destKey, String... srcKeys);
 
+    @Deprecated
+    /**
+     * This method is deprecated due to bug (scan cursor should be unsigned long)
+     * And will be removed on next major release
+     * @see https://github.com/xetorthio/jedis/issues/531 
+     */
     ScanResult<String> scan(int cursor);
+    
+    ScanResult<String> scan(final String cursor);
 }