Fixes #3257 : config validation

Fixed the issue that not a lot of config validation is done. It also fixes the issue
that in some cases instart of shutting down the node, due to the config conflict, a
seperate cluster is created.

This patch doesn't contains logic for structural checking of conflicts for map/queue
etc. But it does contain all the infrastructure.

It also contains the feature where a user can provide a 'token' to that needs to be
the same on all members. E.g. filepath or other configuration settings. This can be
done through the hazelcast.application.validation.token system property.