In 1.0, the property spring.jpa.hibernate.namingstrategy could be
used to configure Hibernate's naming strategy. This was at odds with
most other configuration where binding to namingStrategy would require
a property with some indication that it was two separate words, for
example: naming-strategy, naming_strategy, or namingStrategy

This commit adds a new setter, setNamingstrategy, to JpaProperties so
that an app that was using namingstrategy in 1.0 continues to work
in 1.1.

Issue #928