This commit improves Redis configuration by introducing `@SpringSessionRedisConnectionFactory` qualifier for explicitly declaring a `RedisConnectionFactory` to be used by Spring Session. This is in particular useful in scenarios with multiple `RedisConnectionFactory` beans present in the application context.
Redis configuration is simplified and no longer registers a Spring Session specific `RedisOperations<Object,Object>` bean with the application context.
Users are however able to obtain `RedisOperations<Object,Object>` instance used by Spring Session using newly introduced `@SpringSessionRedisOperations` annotation.
This is necessary because the current version of Spring Session is not
compatible with Boot 2.0.0.M2 and we cannot release against the SNAPSHOTs
Issue gh-833
This commit improves dependency management with the following changes:
- `spring-session-core`: move `javax.servlet-api` from `provided` to `optional` configuration due to introduction of reactive support
- `spring-session-data-redis`: remove Redis driver from `compile` configuration
- Boot samples: delegate Redis driver choice to `spring-boot-starter-data-redis`
- polish `test` configuration dependencies
