Since Flyway has bean properties (with getters and setters)
it can be used to bin directly to the Environment (instead of
copying all the properties into FlywayProperties).
Fixes gh-806
A callback is added in autoconfig, so that if users inject the EntityManagerFactoryBuilder
into their app and use it to create multiple EntityManagerFactories, they all get the
same deferred DDL behaviour. The deferred DDL can also be disabled by setting
spring.jpa.hibernate.deferDdl=true.
Fixes gh-894
