Major commit of alot of work that has been done over the past week.

 - Major overhaul of RedisCluster class
 - Fixed a bug in crc16() when it hashed non standard characters. For example 'Niña' would hash to the wrong slot
 - RedisCluster now inherits StrictRedis to get easy access to all methods so RedisCluster do not have to implement each one. This will reduce the ammount of work when methods change in StrictRedis
 - RedisCluster.__init__ can now ignore to init the slots cache. Used by pipelines in RedisCluster
 - New method get_redis_link_fron_node()
 - When parsing command 'CLUSTER NODES' it will now store if the server is a master or slave
 - Fixed close_existing_connection() to use reset() on StrictRedis connection object
 - No need to parse for keyslot when trying random connection
 - Moved ttl handling out from Exception handling into specific TimeoutError exception handling
 - 'e.message' is deprecated in python 3 so now try to use 'args' and then try 'message' then fail
 - Added pipeline() that will simulate a real pipeline so that no current code will break. A RedisCluster object will now behave as a pipeline() so be carefull. Better impl will be done in the future
 - Added execute_command() so that methods in StrictRedis can be used without reimplement them in RedisCluster and then use send_cluster_command()
 - Implemented almost all commands that requires to be overriden because of limitations in the cluster mode. Currently these methods is overriden [mget, mset, msetnx, randomkey, rename, renamenx brpoplpush, rpoplpush, sort, scan_iter, sscan_iter, hscan_iter, zscan_iter, sdiff, sdiffstore, sinter, sinterstore, smove, sunion, sunionstore]
 - Added methods to help send a command to all servers / all masters and join all results into one data structure. When using these methods that code probably have to be changed/updated to handle the new data format that is different from when using 'StrictRedis'. These methods are [bgrewriteaof, bgsave, client_kill, client_list, client_getname, config_get, config_set, config_resetstat, config_rewrite, dbsize, scho, info, lastsave, ping, save, slowlog_get, slowlog_len, slowlog_reset, time]
 - Added method that will block a command and raise exception if the method is used. There are many different reasons a command is blocked. If you think you have a use case for it and a way to implement it i will implement it. Currently these methods is blocked [client_setname, sentinel, sentinel_get_master_by_addr, sentinel_master, sentinel_monitor, sentinel_remove, sentinel_sentinels, sentinel_set, sentinel_slaves, shutdown, slaveof, restore, watch, unwatch, pfmerge, publish, eval, evalsha, script_exists, script_flush, script_kill, script_load, register_script, move, bitop, zinterstore, zunionstore]
 - Minor changes to setup.py
 - When creating RedisCluster() in test.py it will now decode responses so that it will work with python 3 versions
 - Major overhaul of README.rst with status of all commands, limitations and differences & redisco support
 - Dropped tracking of python support for 2.6 & 3.1