Previously, when Spring Session 1.1.0.M1 and DevTools were declared as
dependencies the application failed to start, because
sessionRedisTemplate could not be resolved.

This commit relaxes the dependency for sessionRedisTemplate in
restartCompatibleRedisSerializerConfigurer from
RedisTemplate<String, ExpiringSession> to RedisTemplate<?, ?> and uses
the bean name in a @Qualifer to ensure that the right RedisTemplate
bean gets injected.

Fixes gh-4895
Closes gh-4896