ISPN-3492 Upgrade JPA Cache Store to 6.0 API
* upgraded to 6.0 SPI
* implemented metadata storage
* statistics for operations on EntityManager
Set up data lengths
Adjust persistence configuration for tests

* Make persistence.xml DB agnostic
* Pass DB specific option via Maven profiles
* Make H2 DB default not to require any prerequisite for running tests
* Add missing entity classes
Make all @AfterMethod public

When running TestNG test in Arquillian, test class has to inherit from Arquillian class
and therefore cannot inherit from other classes like JpaStoreTest and some wrapper class
has to be created. This wrapper class must have access to all @BeforeMethod/@AfterMethod
methods.
Add scenarios for loading/storing values in non-JPACacheStore way

The first test scenario stores values directly via JPA (not via JPAChacheStore)
and verifies that these values are readable and loaded by JPACachStore.
The second one on conrary verifies, that values stored by JPACacheStore
are readable and can be loaded by some other tool than JPACacheStore
(directly via JPA in this case).
ISPN-4072 JPA Cache Store fails to clear entity which conatins ElementCollection

* Fix ISPN-4072
* Add unit tests for entity containing fields with annotations
@Embedded and @ElementCollection