DATAREDIS-246 - RedisCacheManager.getCache() does not match the logical of CompositeCacheManager.

Like other CacheManager implementations, such as EhCacheManager or JCacheCacheManager, the RedisCacheManager asserts to always return a Cache. Therefor a new RedisCache is created and registered when the requested one could not be found. Up to those caches did not get registered properly and did not show up in collection of cache names. 

We changed the implementation so it  makes use of AbstractTransactionalCache introduced in Spring 3.2 which properly registers caches. Additionally the loadRemoteCachesOnStartup switch allows to retrieve and initialize existing caches by loading keys form redis server.