DATAREDIS-184 - Add support for 'SAVE/NOSAVE' to shutdown.

Prepare issue branch.
DATAREDIS-184 - Add support for 'SAVE/NOSAVE' to shutdown.

Created and added 'ShutdownOptions' to 'RedisServerCommands'. The full implementation is available for 'lettuce' and 'srp'. 

When using 'jedis' the command is emulated using lua script via 'eval'.

For 'jredis' the method is not available and will throw 'UnsupportedOperationException'.

Original Pull Request: #47