Make JPA cache store work in Karaf

The JPA cache store does not currently work in Karaf. There are several thing to make it work in OSGi:

• use hibernate-osgi dependency, and possibly change some other dependencies
• JpaStoreConfigurationParser70 should be exposed as a service in Blueprint
• EntityManagerFactory should be obtained from the service registry, similar to https://github.com/hibernate/hibernate-orm/tree/master/documentation/src/main/docbook/quickstart/tutorials/osgi/unmanaged-jpa