allow disabling of Hazelcast support

[esuomi]

Request motivated by the fact that we simply don't have need for it.

There are a few simple and one complex change involved:

1. Make HazelCastConfig require a profile for activation. Very straightforward, just add @Profile("hazelcast") or somesuch.
2. Instruct users to add spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration into application configuration if they wish to disable the feature.
3. Instead of autowiring an instance of HazelcastInstance in application components abstract the needed functionality into an interface and convert the Hazelcast integration into a helper module structure, possibly under rutebanken-helpers following the modularization logic there.

It's worth noting that there already is rutebanken-helper/hazelcast4-helper and the code in tiamat seems to be a direct match with that one. Looking at the version history things have diverged, and the helper in fact has some relevant, useful changes in it already.