DATAREDIS-305 - Add support for HSCAN.

HSCAN is directly supported by jedis and can be emulated for lettuce via eval.

SRP and JRedis will throw UnsupportedOperationException.

We have modified the ScanCursor implementation to take Collection instead of List.

Currently naming for scan commands is not consistent for scan, sscan and hscan. There’s a clean up task for those commands when done with all scan related commands.

Original pull request: #78.
DATAREDIS-312 - Add travis-ci configuration.

setup travis to start a redis-server and test against java 6/7/8.
DATAREDIS-306 - Add support for ZSCAN.

Prepare issue branch.
DATAREDIS-306 - Add support for ZSCAN.

Initial implementation for Jedis via JedisConnection.
Prepared stubs for lettuce, jredis and srp.
Prepared StringRedisConnection delegates.

Missing:
 - Lettuce via LettuceConnection
 - BoundZSetOperations
DATAREDIS-306 - Add support for ZSCAN.

Initial implementation for Jedis via JedisConnection.
Prepared stubs for lettuce, jredis and srp.
Prepared StringRedisConnection delegates.

Missing:
 - BoundZSetOperations
DATAREDIS-306 - Add support for ZSCAN.

ZSCAN is directly supported by jedis and can be emulated for lettuce via eval.

SRP and JRedis will throw UnsupportedOperationException.